diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 5550fee..bcd06c3 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -17,7 +17,7 @@ jobs:
     strategy:
       matrix:
         os: [windows-2022, windows-2019, ubuntu-20.04, ubuntu-22.04]
-        php-version: [7.4, 8.0]
+        php-version: [7.4, 8.0, 8.1, 8.2]
     steps:
     - name: Checkout
       uses: actions/checkout@v3
diff --git a/.gitignore b/.gitignore
index 4fa7f9b..8cb8bd3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,5 @@
 vendor
 composer.lock
 .phpunit.result.cache
-composer.phar
\ No newline at end of file
+composer.phar
+.idea
diff --git a/src/APIHelper.php b/src/APIHelper.php
index 9093d84..debe766 100644
--- a/src/APIHelper.php
+++ b/src/APIHelper.php
@@ -17,11 +17,11 @@ class APIHelper
 {
     /**
     * Replaces template parameters in the given url
-    * @param    string  $url         The query string builder to replace the template parameters
-    * @param    array   $parameters  The parameters to replace in the url
+    * @param string $url         The query string builder to replace the template parameters
+    * @param array $parameters  The parameters to replace in the url
     * @return   string  The processed url
     */
-    public static function appendUrlWithTemplateParameters($url, $parameters, $encode = true)
+    public static function appendUrlWithTemplateParameters(string $url, array $parameters, $encode = true): string
     {
         //perform parameter validation
         if (is_null($url) || !is_string($url)) {
@@ -55,11 +55,11 @@ public static function appendUrlWithTemplateParameters($url, $parameters, $encod
 
     /**
     * Appends the given set of parameters to the given query string
-    * @param    string  $queryBuilder   The query url string to append the parameters
-    * @param    array   $parameters     The parameters to append
+    * @param string $queryBuilder   The query url string to append the parameters
+    * @param array $parameters     The parameters to append
     * @return   void
     */
-    public static function appendUrlWithQueryParameters(&$queryBuilder, $parameters)
+    public static function appendUrlWithQueryParameters(string &$queryBuilder, array $parameters)
     {
         //perform parameter validation
         if (is_null($queryBuilder) || !is_string($queryBuilder)) {
@@ -80,9 +80,9 @@ public static function appendUrlWithQueryParameters(&$queryBuilder, $parameters)
 
     /**
     * Validates and processes the given Url
-    * @param    string  $url The given Url to process
+    * @param string $url The given Url to process
     * @return   string       Pre-processed Url as string */
-    public static function cleanUrl($url)
+    public static function cleanUrl(string $url): string
     {
         //perform parameter validation
         if (is_null($url) || !is_string($url)) {
@@ -106,12 +106,12 @@ public static function cleanUrl($url)
 
     /**
      * Deserialize a Json string
-     * @param  string   $json       A valid Json string
+     * @param string $json       A valid Json string
      * @param  mixed    $instance   Instance of an object to map the json into
-     * @param  boolean  $isArray    Is the Json an object array?
+     * @param boolean $isArray    Is the Json an object array?
      * @return mixed                Decoded Json
      */
-    public static function deserialize($json, $instance = null, $isArray = false)
+    public static function deserialize(string $json, $instance = null, bool $isArray = false)
     {
         if ($instance == null) {
             return json_decode($json, true);
@@ -127,10 +127,10 @@ public static function deserialize($json, $instance = null, $isArray = false)
 
     /**
      * Check if an array isAssociative (has string keys)
-     * @param  array   $arr   A valid array
+     * @param array $arr   A valid array
      * @return boolean        True if the array is Associative, false if it is Indexed
      */
-    private static function isAssociative($arr)
+    private static function isAssociative(array $arr): bool
     {
         foreach ($arr as $key => $value) {
             if (is_string($key)) {
@@ -143,10 +143,10 @@ private static function isAssociative($arr)
 
     /**
      * Prepare a model for form encoding
-     * @param  JsonSerializable  $model  A valid instance of JsonSerializable
+     * @param JsonSerializable $model  A valid instance of JsonSerializable
      * @return array                     The model as a map of key value pairs
      */
-    public static function prepareFormFields($model)
+    public static function prepareFormFields(JsonSerializable $model)
     {
         if (!$model instanceof JsonSerializable) {
             return $model;
diff --git a/src/Configuration.php b/src/Configuration.php
index 4805805..77886ba 100644
--- a/src/Configuration.php
+++ b/src/Configuration.php
@@ -261,10 +261,10 @@ public function getBaseUrl()
 
     /**
      * Get the base uri for a given server in the current environment
-     * @param  string $server Server name
+     * @param string $server Server name
      * @return string         Base URI
      */
-    public function getBaseUri($server = Servers::DEFAULT_)
+    public function getBaseUri(string $server = Servers::DEFAULT_)
     {
         return APIHelper::appendUrlWithTemplateParameters(
             static::$environmentsMap[$this->environment][$server],
diff --git a/src/Http/ApiResponse.php b/src/Http/ApiResponse.php
index d564c73..0da47ee 100644
--- a/src/Http/ApiResponse.php
+++ b/src/Http/ApiResponse.php
@@ -32,11 +32,11 @@ class ApiResponse
 
     /**
      * Create a new instance of a HttpResponse
-     * @param int    $statusCode Response code
+     * @param int $statusCode Response code
      * @param array  $headers    Map of headers
      * @param mixed  $result     The deserialized response
      */
-    public function __construct($statusCode, array $headers, $result)
+    public function __construct(int $statusCode, array $headers, $result)
     {
         $this->statusCode = $statusCode;
         $this->headers = $headers;
diff --git a/src/Http/HttpRequest.php b/src/Http/HttpRequest.php
index 4180db4..a1ba9c9 100644
--- a/src/Http/HttpRequest.php
+++ b/src/Http/HttpRequest.php
@@ -38,12 +38,12 @@ class HttpRequest
     
     /**
      * Create a new HttpRequest
-     * @param string     $httpMethod Http method
+     * @param string|null $httpMethod Http method
      * @param array|null $headers    Map of headers
-     * @param string     $queryUrl   Query url
+     * @param string|null $queryUrl   Query url
      * @param array|null $parameters Map of parameters sent
      */
-    public function __construct($httpMethod = null, array $headers = null, $queryUrl = null, array $parameters = null)
+    public function __construct(string $httpMethod = null, array $headers = null, string $queryUrl = null, array $parameters = null)
     {
         $this->httpMethod = $httpMethod;
         $this->headers = $headers;
@@ -64,7 +64,7 @@ public function getHttpMethod()
      * Set http method
      * @param string $httpMethod Http Method as defined in HttpMethod class
      */
-    public function setHttpMethod($httpMethod)
+    public function setHttpMethod(string $httpMethod)
     {
         $this->httpMethod = $httpMethod;
     }
@@ -100,7 +100,7 @@ public function getQueryUrl()
      * Set query url
      * @param string $queryUrl Query url
      */
-    public function setQueryUrl($queryUrl)
+    public function setQueryUrl(string $queryUrl)
     {
         $this->queryUrl = $queryUrl;
     }
@@ -118,7 +118,7 @@ public function getParameters()
      * Set parameters
      * @param array $parameters Map of input parameters
      */
-    public function setParameters($parameters)
+    public function setParameters(array $parameters)
     {
         $this->parameters = $parameters;
     }
diff --git a/src/Http/HttpResponse.php b/src/Http/HttpResponse.php
index 4ce44f9..361bd50 100644
--- a/src/Http/HttpResponse.php
+++ b/src/Http/HttpResponse.php
@@ -32,11 +32,11 @@ class HttpResponse
 
     /**
      * Create a new instance of a HttpResponse
-     * @param int    $statusCode Response code
+     * @param int $statusCode Response code
      * @param array  $headers    Map of headers
      * @param string $rawBody    Raw response body
      */
-    public function __construct($statusCode, array $headers, $rawBody)
+    public function __construct(int $statusCode, array $headers, string $rawBody)
     {
         $this->statusCode = $statusCode;
         $this->headers = $headers;
diff --git a/src/Messaging/Controllers/APIController.php b/src/Messaging/Controllers/APIController.php
index 99e1fda..9a67190 100644
--- a/src/Messaging/Controllers/APIController.php
+++ b/src/Messaging/Controllers/APIController.php
@@ -34,13 +34,13 @@ public function __construct($config, $httpCallBack = null)
      * Gets a list of your media files. No query parameters are supported.
      *
      * @param string $accountId          User's account ID
-     * @param string $continuationToken  (optional) Continuation token used to retrieve subsequent media.
+     * @param string|null $continuationToken  (optional) Continuation token used to retrieve subsequent media.
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function listMedia(
-        $accountId,
-        $continuationToken = null
+        string $accountId,
+        string $continuationToken = null
     ) {
 
         //prepare query string for API call
@@ -128,8 +128,8 @@ public function listMedia(
      * @throws APIException Thrown if API call fails
      */
     public function getMedia(
-        $accountId,
-        $mediaId
+        string $accountId,
+        string $mediaId
     ) {
 
         //prepare query string for API call
@@ -215,17 +215,17 @@ public function getMedia(
      * @param string $mediaId       The user supplied custom media ID
      * @param string $body          TODO: type description here
      * @param string $contentType   (optional) The media type of the entity-body
-     * @param string $cacheControl  (optional) General-header field is used to specify directives that MUST be obeyed
+     * @param string|null $cacheControl  (optional) General-header field is used to specify directives that MUST be obeyed
      *                              by all caching mechanisms along the request/response chain.
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function uploadMedia(
-        $accountId,
-        $mediaId,
-        $body,
-        $contentType = 'application/octet-stream',
-        $cacheControl = null
+        string $accountId,
+        string $mediaId,
+        string $body,
+        string $contentType = 'application/octet-stream',
+        string $cacheControl = null
     ) {
 
         //prepare query string for API call
@@ -318,8 +318,8 @@ public function uploadMedia(
      * @throws APIException Thrown if API call fails
      */
     public function deleteMedia(
-        $accountId,
-        $mediaId
+        string $accountId,
+        string $mediaId
     ) {
 
         //prepare query string for API call
@@ -399,35 +399,35 @@ public function deleteMedia(
     /**
      * Gets a list of messages based on query parameters.
      *
-     * @param string  $accountId     User's account ID
-     * @param string  $messageId     (optional) The ID of the message to search for. Special characters need to be
+     * @param string $accountId     User's account ID
+     * @param string|null $messageId     (optional) The ID of the message to search for. Special characters need to be
      *                               encoded using URL encoding
-     * @param string  $sourceTn      (optional) The phone number that sent the message
-     * @param string  $destinationTn (optional) The phone number that received the message
-     * @param string  $messageStatus (optional) The status of the message. One of RECEIVED, QUEUED, SENDING, SENT,
+     * @param string|null $sourceTn      (optional) The phone number that sent the message
+     * @param string|null $destinationTn (optional) The phone number that received the message
+     * @param string|null $messageStatus (optional) The status of the message. One of RECEIVED, QUEUED, SENDING, SENT,
      *                               FAILED, DELIVERED, ACCEPTED, UNDELIVERED
-     * @param integer $errorCode     (optional) The error code of the message
-     * @param string  $fromDateTime  (optional) The start of the date range to search in ISO 8601 format. Uses the
+     * @param integer|null $errorCode     (optional) The error code of the message
+     * @param string|null $fromDateTime  (optional) The start of the date range to search in ISO 8601 format. Uses the
      *                               message receive time. The date range to search in is currently 14 days.
-     * @param string  $toDateTime    (optional) The end of the date range to search in ISO 8601 format. Uses the
+     * @param string|null $toDateTime    (optional) The end of the date range to search in ISO 8601 format. Uses the
      *                               message receive time. The date range to search in is currently 14 days.
-     * @param string  $pageToken     (optional) A base64 encoded value used for pagination of results
-     * @param integer $limit         (optional) The maximum records requested in search result. Default 100. The sum of
+     * @param string|null $pageToken     (optional) A base64 encoded value used for pagination of results
+     * @param integer|null $limit         (optional) The maximum records requested in search result. Default 100. The sum of
      *                               limit and after cannot be more than 10000
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function getMessages(
-        $accountId,
-        $messageId = null,
-        $sourceTn = null,
-        $destinationTn = null,
-        $messageStatus = null,
-        $errorCode = null,
-        $fromDateTime = null,
-        $toDateTime = null,
-        $pageToken = null,
-        $limit = null
+        string $accountId,
+        string $messageId = null,
+        string $sourceTn = null,
+        string $destinationTn = null,
+        string $messageStatus = null,
+        int    $errorCode = null,
+        string $fromDateTime = null,
+        string $toDateTime = null,
+        string $pageToken = null,
+        int    $limit = null
     ) {
 
         //prepare query string for API call
@@ -524,14 +524,14 @@ public function getMessages(
     /**
      * Endpoint for sending text messages and picture messages using V2 messaging.
      *
-     * @param string                $accountId User's account ID
+     * @param string $accountId User's account ID
      * @param Models\MessageRequest $body      TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function createMessage(
-        $accountId,
-        $body
+        string                $accountId,
+        Models\MessageRequest $body
     ) {
 
         //prepare query string for API call
diff --git a/src/Messaging/Models/BandwidthCallbackMessage.php b/src/Messaging/Models/BandwidthCallbackMessage.php
index 8f4fe13..ca22d91 100644
--- a/src/Messaging/Models/BandwidthCallbackMessage.php
+++ b/src/Messaging/Models/BandwidthCallbackMessage.php
@@ -66,7 +66,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['time']        = $this->time;
diff --git a/src/Messaging/Models/BandwidthMessage.php b/src/Messaging/Models/BandwidthMessage.php
index 4271f6c..2e0bc0c 100644
--- a/src/Messaging/Models/BandwidthMessage.php
+++ b/src/Messaging/Models/BandwidthMessage.php
@@ -111,7 +111,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['id']            = $this->id;
diff --git a/src/Messaging/Models/BandwidthMessageItem.php b/src/Messaging/Models/BandwidthMessageItem.php
index c310763..2165544 100644
--- a/src/Messaging/Models/BandwidthMessageItem.php
+++ b/src/Messaging/Models/BandwidthMessageItem.php
@@ -136,7 +136,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['messageId']        = $this->messageId;
diff --git a/src/Messaging/Models/BandwidthMessagesList.php b/src/Messaging/Models/BandwidthMessagesList.php
index 75362bc..8b4dc44 100644
--- a/src/Messaging/Models/BandwidthMessagesList.php
+++ b/src/Messaging/Models/BandwidthMessagesList.php
@@ -45,7 +45,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['totalCount'] = $this->totalCount;
diff --git a/src/Messaging/Models/DeferredResult.php b/src/Messaging/Models/DeferredResult.php
index 527c3ef..70c71d7 100644
--- a/src/Messaging/Models/DeferredResult.php
+++ b/src/Messaging/Models/DeferredResult.php
@@ -38,7 +38,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['result']       = $this->result;
diff --git a/src/Messaging/Models/Media.php b/src/Messaging/Models/Media.php
index 659850f..942cd45 100644
--- a/src/Messaging/Models/Media.php
+++ b/src/Messaging/Models/Media.php
@@ -45,7 +45,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['content']       = $this->content;
diff --git a/src/Messaging/Models/MessageRequest.php b/src/Messaging/Models/MessageRequest.php
index 258fecd..08ddbc9 100644
--- a/src/Messaging/Models/MessageRequest.php
+++ b/src/Messaging/Models/MessageRequest.php
@@ -78,7 +78,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['applicationId'] = $this->applicationId;
diff --git a/src/Messaging/Models/PageInfo.php b/src/Messaging/Models/PageInfo.php
index af9587e..2250bf7 100644
--- a/src/Messaging/Models/PageInfo.php
+++ b/src/Messaging/Models/PageInfo.php
@@ -52,7 +52,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['prevPage']      = $this->prevPage;
diff --git a/src/Messaging/Models/Tag.php b/src/Messaging/Models/Tag.php
index 6c51d90..87d0a01 100644
--- a/src/Messaging/Models/Tag.php
+++ b/src/Messaging/Models/Tag.php
@@ -38,7 +38,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['key']   = $this->key;
diff --git a/src/MultiFactorAuth/Controllers/MFAController.php b/src/MultiFactorAuth/Controllers/MFAController.php
index 5ea6322..347bc4d 100644
--- a/src/MultiFactorAuth/Controllers/MFAController.php
+++ b/src/MultiFactorAuth/Controllers/MFAController.php
@@ -34,14 +34,14 @@ public function __construct($config, $httpCallBack = null)
      * Multi-Factor authentication with Bandwidth Voice services. Allows for a user to send an MFA code via
      * a phone call.
      *
-     * @param string                            $accountId Bandwidth Account ID with Voice service enabled
+     * @param string $accountId Bandwidth Account ID with Voice service enabled
      * @param Models\TwoFactorCodeRequestSchema $body      TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function createVoiceTwoFactor(
-        $accountId,
-        $body
+        string                            $accountId,
+        Models\TwoFactorCodeRequestSchema $body
     ) {
 
         //prepare query string for API call
@@ -128,14 +128,14 @@ public function createVoiceTwoFactor(
      * Multi-Factor authentication with Bandwidth Messaging services. Allows a user to send an MFA code via
      * a text message (SMS).
      *
-     * @param string                            $accountId Bandwidth Account ID with Messaging service enabled
+     * @param string $accountId Bandwidth Account ID with Messaging service enabled
      * @param Models\TwoFactorCodeRequestSchema $body      TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function createMessagingTwoFactor(
-        $accountId,
-        $body
+        string                            $accountId,
+        Models\TwoFactorCodeRequestSchema $body
     ) {
 
         //prepare query string for API call
@@ -221,14 +221,14 @@ public function createMessagingTwoFactor(
     /**
      * Allows a user to verify an MFA code.
      *
-     * @param string                              $accountId Bandwidth Account ID with Two-Factor enabled
+     * @param string $accountId Bandwidth Account ID with Two-Factor enabled
      * @param Models\TwoFactorVerifyRequestSchema $body      TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function createVerifyTwoFactor(
-        $accountId,
-        $body
+        string                              $accountId,
+        Models\TwoFactorVerifyRequestSchema $body
     ) {
 
         //prepare query string for API call
diff --git a/src/MultiFactorAuth/Models/TwoFactorCodeRequestSchema.php b/src/MultiFactorAuth/Models/TwoFactorCodeRequestSchema.php
index 1d8e0ee..4d93710 100644
--- a/src/MultiFactorAuth/Models/TwoFactorCodeRequestSchema.php
+++ b/src/MultiFactorAuth/Models/TwoFactorCodeRequestSchema.php
@@ -76,7 +76,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['to']            = $this->to;
diff --git a/src/MultiFactorAuth/Models/TwoFactorMessagingResponse.php b/src/MultiFactorAuth/Models/TwoFactorMessagingResponse.php
index d68e75e..3ffe87b 100644
--- a/src/MultiFactorAuth/Models/TwoFactorMessagingResponse.php
+++ b/src/MultiFactorAuth/Models/TwoFactorMessagingResponse.php
@@ -31,7 +31,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['messageId'] = $this->messageId;
diff --git a/src/MultiFactorAuth/Models/TwoFactorVerifyCodeResponse.php b/src/MultiFactorAuth/Models/TwoFactorVerifyCodeResponse.php
index d4275e6..d689f81 100644
--- a/src/MultiFactorAuth/Models/TwoFactorVerifyCodeResponse.php
+++ b/src/MultiFactorAuth/Models/TwoFactorVerifyCodeResponse.php
@@ -31,7 +31,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['valid'] = $this->valid;
diff --git a/src/MultiFactorAuth/Models/TwoFactorVerifyRequestSchema.php b/src/MultiFactorAuth/Models/TwoFactorVerifyRequestSchema.php
index 984a75e..ebaa94d 100644
--- a/src/MultiFactorAuth/Models/TwoFactorVerifyRequestSchema.php
+++ b/src/MultiFactorAuth/Models/TwoFactorVerifyRequestSchema.php
@@ -48,6 +48,10 @@ class TwoFactorVerifyRequestSchema implements \JsonSerializable
      * @var string $code public property
      */
     public $code;
+    /**
+     * @var int
+     */
+    public $digits;
 
     /**
      * Constructor to set initial or default values of member properties
@@ -66,7 +70,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['to']                      = $this->to;
diff --git a/src/MultiFactorAuth/Models/TwoFactorVoiceResponse.php b/src/MultiFactorAuth/Models/TwoFactorVoiceResponse.php
index 25bf261..c8f4b69 100644
--- a/src/MultiFactorAuth/Models/TwoFactorVoiceResponse.php
+++ b/src/MultiFactorAuth/Models/TwoFactorVoiceResponse.php
@@ -31,7 +31,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['callId'] = $this->callId;
diff --git a/src/PhoneNumberLookup/Controllers/APIController.php b/src/PhoneNumberLookup/Controllers/APIController.php
index 6ee286a..6ab00ee 100644
--- a/src/PhoneNumberLookup/Controllers/APIController.php
+++ b/src/PhoneNumberLookup/Controllers/APIController.php
@@ -33,14 +33,14 @@ public function __construct($config, $httpCallBack = null)
     /**
      * Create a TN Lookup Order.
      *
-     * @param string              $accountId The ID of the Bandwidth account that the user belongs to.
+     * @param string $accountId The ID of the Bandwidth account that the user belongs to.
      * @param Models\OrderRequest $body      TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function createLookupRequest(
-        $accountId,
-        $body
+        string              $accountId,
+        Models\OrderRequest $body
     ) {
 
         //prepare query string for API call
@@ -939,8 +939,8 @@ public function createLookupRequest(
      * @throws APIException Thrown if API call fails
      */
     public function getLookupRequestStatus(
-        $accountId,
-        $requestId
+        string $accountId,
+        string $requestId
     ) {
 
         //prepare query string for API call
diff --git a/src/Utils/DateTimeHelper.php b/src/Utils/DateTimeHelper.php
index d7aa394..f2b4e58 100644
--- a/src/Utils/DateTimeHelper.php
+++ b/src/Utils/DateTimeHelper.php
@@ -29,7 +29,7 @@ class DateTimeHelper
      * @param \DateTime|null $date The DateTime object to convert
      * @return string|null The datetime as a string in simple date format
      */
-    public static function toSimpleDate($date)
+    public static function toSimpleDate(?DateTime $date)
     {
         if (is_null($date)) {
             return null;
@@ -45,7 +45,7 @@ public static function toSimpleDate($date)
      * @param array|null $dates The array of DateTime objects to convert
      * @return array|null The array of datetime strings in simple date format
      */
-    public static function toSimpleDateArray($dates)
+    public static function toSimpleDateArray(?array $dates)
     {
         if (is_null($dates)) {
             return null;
@@ -59,7 +59,7 @@ public static function toSimpleDateArray($dates)
      * @param string|null $date A datetime string in simple date format
      * @return \DateTime|null The parsed DateTime object
      */
-    public static function fromSimpleDate($date)
+    public static function fromSimpleDate(?string $date)
     {
         if (is_null($date)) {
             return null;
@@ -79,7 +79,7 @@ public static function fromSimpleDate($date)
      * @param array|null $dates An array of datetime strings in simple date format
      * @return array|null An array of parsed DateTime objects
      */
-    public static function fromSimpleDateArray($dates)
+    public static function fromSimpleDateArray(?array $dates)
     {
         if (is_null($dates)) {
             return null;
@@ -94,7 +94,7 @@ public static function fromSimpleDateArray($dates)
      * @param \DateTime|null $datetime The DateTime object to convert
      * @return string|null The datetime as a string in Rfc1123 format
      */
-    public static function toRfc1123DateTime($datetime)
+    public static function toRfc1123DateTime(?DateTime $datetime)
     {
         if (is_null($datetime)) {
             return null;
@@ -110,7 +110,7 @@ public static function toRfc1123DateTime($datetime)
      * @param array|null $datetimes The array of DateTime objects to convert
      * @return array|null The array of datetime strings in Rfc1123 format
      */
-    public static function toRfc1123DateTimeArray($datetimes)
+    public static function toRfc1123DateTimeArray(?array $datetimes)
     {
         if (is_null($datetimes)) {
             return null;
@@ -124,7 +124,7 @@ public static function toRfc1123DateTimeArray($datetimes)
      * @param string|null $datetime A datetime string in Rfc1123 format
      * @return \DateTime|null The parsed DateTime object
      */
-    public static function fromRfc1123DateTime($datetime)
+    public static function fromRfc1123DateTime(?string $datetime)
     {
         if (is_null($datetime)) {
             return null;
@@ -144,7 +144,7 @@ public static function fromRfc1123DateTime($datetime)
      * @param array|null $datetimes An array of datetime strings in Rfc1123 format
      * @return array|null An array of parsed DateTime objects
      */
-    public static function fromRfc1123DateTimeArray($datetimes)
+    public static function fromRfc1123DateTimeArray(?array $datetimes)
     {
         if (is_null($datetimes)) {
             return null;
@@ -159,7 +159,7 @@ public static function fromRfc1123DateTimeArray($datetimes)
      * @param \DateTime|null $datetime The DateTime object to convert
      * @return string|null The datetime as a string in Rfc3339 format
      */
-    public static function toRfc3339DateTime($datetime)
+    public static function toRfc3339DateTime(?DateTime $datetime)
     {
         if (is_null($datetime)) {
             return null;
@@ -175,7 +175,7 @@ public static function toRfc3339DateTime($datetime)
      * @param array|null $datetimes The array of DateTime objects to convert
      * @return array|null The array of datetime strings in Rfc3339 format
      */
-    public static function toRfc3339DateTimeArray($datetimes)
+    public static function toRfc3339DateTimeArray(?array $datetimes)
     {
         if (is_null($datetimes)) {
             return null;
@@ -189,7 +189,7 @@ public static function toRfc3339DateTimeArray($datetimes)
      * @param string|null $datetime A datetime string in Rfc3339 format
      * @return \DateTime|null The parsed DateTime object
      */
-    public static function fromRfc3339DateTime($datetime)
+    public static function fromRfc3339DateTime(?string $datetime)
     {
         if (is_null($datetime)) {
             return null;
@@ -224,7 +224,7 @@ public static function fromRfc3339DateTime($datetime)
      * @param array|null $datetimes An array of datetime strings in Rfc3339 format
      * @return array|null An array of parsed DateTime objects
      */
-    public static function fromRfc3339DateTimeArray($datetimes)
+    public static function fromRfc3339DateTimeArray(?array $datetimes)
     {
         if (is_null($datetimes)) {
             return null;
@@ -239,7 +239,7 @@ public static function fromRfc3339DateTimeArray($datetimes)
      * @param \DateTime|null $datetime The DateTime object to convert
      * @return int|null The converted Unix Timestamp
      */
-    public static function toUnixTimestamp($datetime)
+    public static function toUnixTimestamp(?DateTime $datetime)
     {
         if (is_null($datetime)) {
             return null;
@@ -255,7 +255,7 @@ public static function toUnixTimestamp($datetime)
      * @param array|null $datetimes The array of DateTime objects to convert
      * @return array|null The array of integers representing date-time in Unix timestamp
      */
-    public static function toUnixTimestampArray($datetimes)
+    public static function toUnixTimestampArray(?array $datetimes)
     {
         if (is_null($datetimes)) {
             return null;
@@ -269,7 +269,7 @@ public static function toUnixTimestampArray($datetimes)
      * @param string|null $datetime The Unix Timestamp
      * @return \DateTime|null The parsed DateTime object
      */
-    public static function fromUnixTimestamp($datetime)
+    public static function fromUnixTimestamp(?string $datetime)
     {
         if (is_null($datetime)) {
             return null;
@@ -289,7 +289,7 @@ public static function fromUnixTimestamp($datetime)
      * @param array|null $datetimes An array of Unix Timestamps
      * @return array|null An array of parsed DateTime objects
      */
-    public static function fromUnixTimestampArray($datetimes)
+    public static function fromUnixTimestampArray(?array $datetimes)
     {
         if (is_null($datetimes)) {
             return null;
diff --git a/src/Voice/Bxml/Bridge.php b/src/Voice/Bxml/Bridge.php
index c4c071f..8a1aec7 100644
--- a/src/Voice/Bxml/Bridge.php
+++ b/src/Voice/Bxml/Bridge.php
@@ -9,16 +9,74 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Bridge extends Verb {
+    /**
+     * @var string
+     */
+    private $fallbackPassword;
+    /**
+     * @var string
+     */
+    private $fallbackUsername;
+    /**
+     * @var string
+     */
+    private $bridgeTargetCompleteFallbackMethod;
+    /**
+     * @var string
+     */
+    private $bridgeTargetCompleteFallbackUrl;
+    /**
+     * @var string
+     */
+    private $bridgeCompleteFallbackMethod;
+    /**
+     * @var string
+     */
+    private $bridgeCompleteFallbackUrl;
+    /**
+     * @var string
+     */
+    private $tag;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
+    /**
+     * @var string
+     */
+    private $bridgeTargetCompleteMethod;
+    /**
+     * @var string
+     */
+    private $bridgeTargetCompleteUrl;
+    /**
+     * @var string
+     */
+    private $bridgeCompleteMethod;
+    /**
+     * @var string
+     */
+    private $bridgeCompleteUrl;
+    /**
+     * @var string
+     */
+    private $targetCall;
 
     /**
      * Constructor for Bridge
      *
      * @param string $targetCall The target call ID of the bridge
      */
-    public function __construct($targetCall) {
+    public function __construct(string $targetCall) {
         $this->targetCall = $targetCall;
     }
 
@@ -27,7 +85,7 @@ public function __construct($targetCall) {
      *
      * @param string $bridgeCompleteUrl URL to send the bridge complete event to
      */
-    public function bridgeCompleteUrl($bridgeCompleteUrl) {
+    public function bridgeCompleteUrl(string $bridgeCompleteUrl) {
         $this->bridgeCompleteUrl = $bridgeCompleteUrl;
     }
 
@@ -36,7 +94,7 @@ public function bridgeCompleteUrl($bridgeCompleteUrl) {
      *
      * @param string $bridgeCompleteMethod HTTP method to send the bridge complete event
      */
-    public function bridgeCompleteMethod($bridgeCompleteMethod) {
+    public function bridgeCompleteMethod(string $bridgeCompleteMethod) {
         $this->bridgeCompleteMethod = $bridgeCompleteMethod;
     }
 
@@ -45,7 +103,7 @@ public function bridgeCompleteMethod($bridgeCompleteMethod) {
      *
      * @param string $bridgeTargetCompleteUrl URL to send the bridge target complete event to
      */
-    public function bridgeTargetCompleteUrl($bridgeTargetCompleteUrl) {
+    public function bridgeTargetCompleteUrl(string $bridgeTargetCompleteUrl) {
         $this->bridgeTargetCompleteUrl = $bridgeTargetCompleteUrl;
     }
 
@@ -54,7 +112,7 @@ public function bridgeTargetCompleteUrl($bridgeTargetCompleteUrl) {
      *
      * @param string $bridgeTargetCompleteMethod HTTP method to send the bridge target complete event
      */
-    public function bridgeTargetCompleteMethod($bridgeTargetCompleteMethod) {
+    public function bridgeTargetCompleteMethod(string $bridgeTargetCompleteMethod) {
         $this->bridgeTargetCompleteMethod = $bridgeTargetCompleteMethod;
     }
 
@@ -63,7 +121,7 @@ public function bridgeTargetCompleteMethod($bridgeTargetCompleteMethod) {
      *
      * @param string $username HTTP basic auth username for sending events
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -72,7 +130,7 @@ public function username($username) {
      *
      * @param string $password HTTP basic auth password for sending events
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -81,7 +139,7 @@ public function password($password) {
      *
      * @param string $tag String to include in events
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
@@ -90,7 +148,7 @@ public function tag($tag) {
      *
      * @param string $bridgeCompleteFallbackUrl Fallback URL for bridge complete callback events
      */
-    public function bridgeCompleteFallbackUrl($bridgeCompleteFallbackUrl) {
+    public function bridgeCompleteFallbackUrl(string $bridgeCompleteFallbackUrl) {
         $this->bridgeCompleteFallbackUrl = $bridgeCompleteFallbackUrl;
     }
 
@@ -99,7 +157,7 @@ public function bridgeCompleteFallbackUrl($bridgeCompleteFallbackUrl) {
      *
      * @param string $bridgeCompleteFallbackMethod HTTP method for bridge complete fallback requests 
      */
-    public function bridgeCompleteFallbackMethod($bridgeCompleteFallbackMethod) {
+    public function bridgeCompleteFallbackMethod(string $bridgeCompleteFallbackMethod) {
         $this->bridgeCompleteFallbackMethod = $bridgeCompleteFallbackMethod;
     }
 
@@ -108,7 +166,7 @@ public function bridgeCompleteFallbackMethod($bridgeCompleteFallbackMethod) {
      *
      * @param string $bridgeTargetCompleteFallbackUrl Fallback URL for bridge target complete callback events 
      */
-    public function bridgeTargetCompleteFallbackUrl($bridgeTargetCompleteFallbackUrl) {
+    public function bridgeTargetCompleteFallbackUrl(string $bridgeTargetCompleteFallbackUrl) {
         $this->bridgeTargetCompleteFallbackUrl = $bridgeTargetCompleteFallbackUrl;
     }
 
@@ -117,7 +175,7 @@ public function bridgeTargetCompleteFallbackUrl($bridgeTargetCompleteFallbackUrl
      *
      * @param string $bridgeTargetCompleteFallbackMethod HTTP method for bridge target complete fallback events 
      */
-    public function bridgeTargetCompleteFallbackMethod($bridgeTargetCompleteFallbackMethod) {
+    public function bridgeTargetCompleteFallbackMethod(string $bridgeTargetCompleteFallbackMethod) {
         $this->bridgeTargetCompleteFallbackMethod = $bridgeTargetCompleteFallbackMethod;
     }
 
@@ -126,7 +184,7 @@ public function bridgeTargetCompleteFallbackMethod($bridgeTargetCompleteFallback
      *
      * @param string $fallbackUsername HTTP basic auth username for fallback events
      */
-    public function fallbackUsername($fallbackUsername) {
+    public function fallbackUsername(string $fallbackUsername) {
         $this->fallbackUsername = $fallbackUsername;
     }
 
@@ -135,11 +193,11 @@ public function fallbackUsername($fallbackUsername) {
      *
      * @param string $fallbackPassword HTTP basic auth password 
      */
-    public function fallbackPassword($fallbackPassword) {
+    public function fallbackPassword(string $fallbackPassword) {
         $this->fallbackPassword = $fallbackPassword;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Bridge");
 
         $element->appendChild($doc->createTextNode($this->targetCall));
diff --git a/src/Voice/Bxml/Bxml.php b/src/Voice/Bxml/Bxml.php
index 6030401..6e45adc 100644
--- a/src/Voice/Bxml/Bxml.php
+++ b/src/Voice/Bxml/Bxml.php
@@ -12,6 +12,10 @@
 use DOMDocument;
 
 class Bxml {
+    /**
+     * @var array
+     */
+    private $verbs;
 
     /**
      * Creates the Bxml class with an empty list of verbs
@@ -25,7 +29,7 @@ public function __construct() {
      *
      * @param Verb $verb The verb to add to the list
      */
-    public function addVerb($verb) {
+    public function addVerb(Verb $verb) {
         array_push($this->verbs, $verb);
     }
 
diff --git a/src/Voice/Bxml/Conference.php b/src/Voice/Bxml/Conference.php
index 3dae673..60be9a8 100644
--- a/src/Voice/Bxml/Conference.php
+++ b/src/Voice/Bxml/Conference.php
@@ -9,16 +9,70 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Conference extends Verb {
+    /**
+     * @var string
+     */
+    private $fallbackPassword;
+    /**
+     * @var string
+     */
+    private $fallbackUsername;
+    /**
+     * @var string
+     */
+    private $conferenceEventFallbackMethod;
+    /**
+     * @var string
+     */
+    private $conferenceEventFallbackUrl;
+    /**
+     * @var bool
+     */
+    private $hold;
+    /**
+     * @var bool
+     */
+    private $mute;
+    /**
+     * @var string
+     */
+    private $callIdsToCoach;
+    /**
+     * @var string
+     */
+    private $conferenceEventMethod;
+    /**
+     * @var string
+     */
+    private $conferenceEventUrl;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
+    /**
+     * @var string
+     */
+    private $tag;
+    /**
+     * @var string
+     */
+    private $conferenceName;
 
     /**
      * Constructor for Conference
      *
      * @param string $conferenceName The name of the conference 
      */
-    public function __construct($conferenceName) {
+    public function __construct(string $conferenceName) {
         $this->conferenceName = $conferenceName;
     }
 
@@ -27,7 +81,7 @@ public function __construct($conferenceName) {
      *
      * @param string $tag A custom string to be included in callbacks 
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
@@ -36,7 +90,7 @@ public function tag($tag) {
      *
      * @param string $username Username for basic auth for callbacks
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -45,7 +99,7 @@ public function username($username) {
      *
      * @param string $password Password for basic auth for callbacks
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -54,7 +108,7 @@ public function password($password) {
      *
      * @param string $conferenceEventUrl URL to receive conference events 
      */
-    public function conferenceEventUrl($conferenceEventUrl) {
+    public function conferenceEventUrl(string $conferenceEventUrl) {
         $this->conferenceEventUrl = $conferenceEventUrl;
     }
 
@@ -63,7 +117,7 @@ public function conferenceEventUrl($conferenceEventUrl) {
      *
      * @param string $conferenceEventMethod HTTP method for conference events 
      */
-    public function conferenceEventMethod($conferenceEventMethod) {
+    public function conferenceEventMethod(string $conferenceEventMethod) {
         $this->conferenceEventMethod = $conferenceEventMethod;
     }
 
@@ -72,7 +126,7 @@ public function conferenceEventMethod($conferenceEventMethod) {
      *
      * @param string $callIdsToCoach A string of comma separated call IDs to coach 
      */
-    public function callIdsToCoach($callIdsToCoach) {
+    public function callIdsToCoach(string $callIdsToCoach) {
         $this->callIdsToCoach = $callIdsToCoach;
     }
 
@@ -81,7 +135,7 @@ public function callIdsToCoach($callIdsToCoach) {
      *
      * @param array $callIdsToCoach An array of call IDs to coach 
      */
-    public function callIdsToCoachArray($callIdsToCoach) {
+    public function callIdsToCoachArray(array $callIdsToCoach) {
         $this->callIdsToCoach = implode(",", $callIdsToCoach);
     }
 
@@ -90,7 +144,7 @@ public function callIdsToCoachArray($callIdsToCoach) {
      *
      * @param boolean $mute Determines if conference members should be on mute
      */
-    public function mute($mute) {
+    public function mute(bool $mute) {
         $this->mute = $mute;
     }
 
@@ -99,7 +153,7 @@ public function mute($mute) {
      *
      * @param boolean $hold Determines if conference members should be on hold
      */
-    public function hold($hold) {
+    public function hold(bool $hold) {
         $this->hold = $hold;
     }
 
@@ -108,7 +162,7 @@ public function hold($hold) {
      *
      * @param string $conferenceEventFallbackUrl Fallback url for conference events
      */
-    public function conferenceEventFallbackUrl($conferenceEventFallbackUrl) {
+    public function conferenceEventFallbackUrl(string $conferenceEventFallbackUrl) {
         $this->conferenceEventFallbackUrl = $conferenceEventFallbackUrl;
     }
 
@@ -117,7 +171,7 @@ public function conferenceEventFallbackUrl($conferenceEventFallbackUrl) {
      *
      * @param string $conferenceEventFallbackMethod HTTP method for fallback events 
      */
-    public function conferenceEventFallbackMethod($conferenceEventFallbackMethod) {
+    public function conferenceEventFallbackMethod(string $conferenceEventFallbackMethod) {
         $this->conferenceEventFallbackMethod = $conferenceEventFallbackMethod;
     }
 
@@ -126,7 +180,7 @@ public function conferenceEventFallbackMethod($conferenceEventFallbackMethod) {
      *
      * @param string $fallbackUsername HTTP basic auth username for fallback events
      */
-    public function fallbackUsername($fallbackUsername) {
+    public function fallbackUsername(string $fallbackUsername) {
         $this->fallbackUsername = $fallbackUsername;
     }
 
@@ -135,11 +189,11 @@ public function fallbackUsername($fallbackUsername) {
      *
      * @param string $fallbackPassword HTTP basic auth password for fallback events
      */
-    public function fallbackPassword($fallbackPassword) {
+    public function fallbackPassword(string $fallbackPassword) {
         $this->fallbackPassword = $fallbackPassword;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Conference");
 
         $element->appendChild($doc->createTextNode($this->conferenceName));
diff --git a/src/Voice/Bxml/Forward.php b/src/Voice/Bxml/Forward.php
index b5545fa..6a7b440 100644
--- a/src/Voice/Bxml/Forward.php
+++ b/src/Voice/Bxml/Forward.php
@@ -9,16 +9,38 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Forward extends Verb {
+    /**
+     * @var string
+     */
+    private $diversionReason;
+    /**
+     * @var string
+     */
+    private $diversionTreatment;
+    /**
+     * @var string
+     */
+    private $callTimeout;
+    /**
+     * @var string
+     */
+    private $from;
+    /**
+     * @var string
+     */
+    private $to;
 
     /**
      * Sets the to attribute for Forward
      *
      * @param string $to The phone number to receive the phone call 
      */
-    public function to($to) {
+    public function to(string $to) {
         $this->to = $to;
     }
 
@@ -27,7 +49,7 @@ public function to($to) {
      *
      * @param string $from The phone number to make the phone call
      */
-    public function from($from) {
+    public function from(string $from) {
         $this->from = $from;
     }
 
@@ -36,7 +58,7 @@ public function from($from) {
      *
      * @param string $callTimeout The timeout in seconds for the phone call 
      */
-    public function callTimeout($callTimeout) {
+    public function callTimeout(string $callTimeout) {
         $this->callTimeout = $callTimeout;
     }
 
@@ -45,7 +67,7 @@ public function callTimeout($callTimeout) {
      *
      * @param string $diversionTreatment The diversion treatment for the phone call 
      */
-    public function diversionTreatment($diversionTreatment) {
+    public function diversionTreatment(string $diversionTreatment) {
         $this->diversionTreatment = $diversionTreatment;
     }
 
@@ -54,11 +76,11 @@ public function diversionTreatment($diversionTreatment) {
      *
      * @param string $diversionReason The diversion treatment for the phone call 
      */
-    public function diversionReason($diversionReason) {
+    public function diversionReason(string $diversionReason) {
         $this->diversionReason = $diversionReason;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Forward");
 
         if(isset($this->to)) {
diff --git a/src/Voice/Bxml/Gather.php b/src/Voice/Bxml/Gather.php
index 5197507..b5664c9 100644
--- a/src/Voice/Bxml/Gather.php
+++ b/src/Voice/Bxml/Gather.php
@@ -9,18 +9,88 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 require_once "SpeakSentence.php";
 require_once "PlayAudio.php";
 
 class Gather extends Verb {
+    /**
+     * @var string
+     */
+    private $fallbackPassword;
+    /**
+     * @var string
+     */
+    private $fallbackUsername;
+    /**
+     * @var string
+     */
+    private $gatherFallbackMethod;
+    /**
+     * @var string
+     */
+    private $gatherFallbackUrl;
+    /**
+     * @var SpeakSentence
+     */
+    private $speakSentence;
+    /**
+     * @var int
+     */
+    private $repeatCount;
+    /**
+     * @var PlayAudio
+     */
+    private $playAudio;
+    /**
+     * @var int
+     */
+    private $firstDigitTimeout;
+    /**
+     * @var int
+     */
+    private $interDigitTimeout;
+    /**
+     * @var int
+     */
+    private $maxDigits;
+    /**
+     * @var string
+     */
+    private $terminatingDigits;
+    /**
+     * @var string
+     */
+    private $tag;
+    /**
+     * @var string
+     */
+    private $gatherMethod;
+    /**
+     * @var string
+     */
+    private $gatherUrl;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
+    /**
+     * @var array(Verb)
+     */
+    private $nestableVerbs;
 
     /**
      * Sets the username attribute for Gather
      *
      * @param string $username The username for http authentication for the gather callback
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -29,7 +99,7 @@ public function username($username) {
      *
      * @param string $password The password for http authentication for the gather callback
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -38,7 +108,7 @@ public function password($password) {
      *
      * @param string $gatherUrl The url to receive the gather callback 
      */
-    public function gatherUrl($gatherUrl) {
+    public function gatherUrl(string $gatherUrl) {
         $this->gatherUrl = $gatherUrl;
     }
 
@@ -47,7 +117,7 @@ public function gatherUrl($gatherUrl) {
      *
      * @param string $gatherMethod The http method to send the gather callback 
      */
-    public function gatherMethod($gatherMethod) {
+    public function gatherMethod(string $gatherMethod) {
         $this->gatherMethod = $gatherMethod;
     }
 
@@ -56,7 +126,7 @@ public function gatherMethod($gatherMethod) {
      *
      * @param string $tag A custom string to be included in callbacks 
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
@@ -65,7 +135,7 @@ public function tag($tag) {
      *
      * @param string $terminatingDigits Digits to terminate the gather
      */
-    public function terminatingDigits($terminatingDigits) {
+    public function terminatingDigits(string $terminatingDigits) {
         $this->terminatingDigits = $terminatingDigits;
     }
 
@@ -74,7 +144,7 @@ public function terminatingDigits($terminatingDigits) {
      *
      * @param int $maxDigits The maximum number of digits to collect in the gather
      */
-    public function maxDigits($maxDigits) {
+    public function maxDigits(int $maxDigits) {
         $this->maxDigits = $maxDigits;
     }
 
@@ -83,7 +153,7 @@ public function maxDigits($maxDigits) {
      *
      * @param int $interDigitTimeout The time in secods between digit presses before timing out
      */
-    public function interDigitTimeout($interDigitTimeout) {
+    public function interDigitTimeout(int $interDigitTimeout) {
         $this->interDigitTimeout = $interDigitTimeout;
     }
 
@@ -92,7 +162,7 @@ public function interDigitTimeout($interDigitTimeout) {
      *
      * @param int $firstDigitTimeout The time in seconds before the first digit is pressed before timing out
      */
-    public function firstDigitTimeout($firstDigitTimeout) {
+    public function firstDigitTimeout(int $firstDigitTimeout) {
         $this->firstDigitTimeout = $firstDigitTimeout;
     }
 
@@ -101,7 +171,7 @@ public function firstDigitTimeout($firstDigitTimeout) {
      *
      * @param PlayAudio $playAudio The PlayAudio tag to include in the Gather
      */
-    public function playAudio($playAudio) {
+    public function playAudio(PlayAudio $playAudio) {
         $this->playAudio = $playAudio;
         $this->addNestableVerb($playAudio);
     }
@@ -111,7 +181,7 @@ public function playAudio($playAudio) {
      *
      * @param int $repeatCount The number of times to repeat the played audio
      */
-    public function repeatCount($repeatCount) {
+    public function repeatCount(int $repeatCount) {
         $this->repeatCount = $repeatCount;
     }
 
@@ -120,7 +190,7 @@ public function repeatCount($repeatCount) {
      *
      * @param SpeakSentence $speakSentence The SpeakSentence tag to include in the Gather
      */
-    public function speakSentence($speakSentence) {
+    public function speakSentence(SpeakSentence $speakSentence) {
         $this->speakSentence = $speakSentence;
         $this->addNestableVerb($speakSentence);
     }
@@ -130,7 +200,7 @@ public function speakSentence($speakSentence) {
      *
      * @param string $gatherFallbackUrl Fallback url for gather events
      */
-    public function gatherFallbackUrl($gatherFallbackUrl) {
+    public function gatherFallbackUrl(string $gatherFallbackUrl) {
         $this->gatherFallbackUrl = $gatherFallbackUrl;
     }
 
@@ -139,7 +209,7 @@ public function gatherFallbackUrl($gatherFallbackUrl) {
      *
      * @param string $gatherFallbackMethod HTTP method for fallback events
      */
-    public function gatherFallbackMethod($gatherFallbackMethod) {
+    public function gatherFallbackMethod(string $gatherFallbackMethod) {
         $this->gatherFallbackMethod = $gatherFallbackMethod;
     }
 
@@ -148,7 +218,7 @@ public function gatherFallbackMethod($gatherFallbackMethod) {
      *
      * @param string $fallbackUsername HTTP basic auth username for fallback events
      */
-    public function fallbackUsername($fallbackUsername) {
+    public function fallbackUsername(string $fallbackUsername) {
         $this->fallbackUsername = $fallbackUsername;
     }
 
@@ -157,7 +227,7 @@ public function fallbackUsername($fallbackUsername) {
      *
      * @param string $fallbackPassword HTTP basic auth password for fallback events
      */
-    public function fallbackPassword($fallbackPassword) {
+    public function fallbackPassword(string $fallbackPassword) {
         $this->fallbackPassword = $fallbackPassword;
     }
 
@@ -173,7 +243,7 @@ private function addNestableVerb($verb) {
         array_push($this->nestableVerbs, $verb);
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Gather");
 
         if(isset($this->username)) {
diff --git a/src/Voice/Bxml/Hangup.php b/src/Voice/Bxml/Hangup.php
index e0afd61..1b9edcd 100644
--- a/src/Voice/Bxml/Hangup.php
+++ b/src/Voice/Bxml/Hangup.php
@@ -9,11 +9,13 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Hangup extends Verb {
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Hangup");
         return $element;
     }
diff --git a/src/Voice/Bxml/Pause.php b/src/Voice/Bxml/Pause.php
index 865291b..a9a5442 100644
--- a/src/Voice/Bxml/Pause.php
+++ b/src/Voice/Bxml/Pause.php
@@ -9,20 +9,26 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Pause extends Verb {
+    /**
+     * @var float
+     */
+    private $duration;
 
     /**
      * Sets the duration attribute for Pause
      *
      * @param float $duration The duration in seconds for the pause 
      */
-    public function duration($duration) {
+    public function duration(float $duration) {
         $this->duration = $duration;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Pause");
 
         if(isset($this->duration)) {
diff --git a/src/Voice/Bxml/PauseRecording.php b/src/Voice/Bxml/PauseRecording.php
index 4d17ad1..0023b11 100644
--- a/src/Voice/Bxml/PauseRecording.php
+++ b/src/Voice/Bxml/PauseRecording.php
@@ -9,11 +9,13 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class PauseRecording extends Verb {
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("PauseRecording");
         return $element;
     }
diff --git a/src/Voice/Bxml/PhoneNumber.php b/src/Voice/Bxml/PhoneNumber.php
index e41a902..869f0a2 100644
--- a/src/Voice/Bxml/PhoneNumber.php
+++ b/src/Voice/Bxml/PhoneNumber.php
@@ -9,16 +9,66 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class PhoneNumber extends Verb {
+    /**
+     * @var string
+     */
+    private $fallbackPassword;
+    /**
+     * @var string
+     */
+    private $fallbackUsername;
+    /**
+     * @var string
+     */
+    private $transferAnswerFallbackMethod;
+    /**
+     * @var string
+     */
+    private $transferAnswerFallbackUrl;
+    /**
+     * @var string
+     */
+    private $tag;
+    /**
+     * @var string
+     */
+    private $transferDisconnectMethod;
+    /**
+     * @var string
+     */
+    private $transferDisconnectUrl;
+    /**
+     * @var string
+     */
+    private $transferAnswerMethod;
+    /**
+     * @var string
+     */
+    private $transferAnswerUrl;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
+    /**
+     * @var string
+     */
+    private $phoneNumber;
 
     /**
      * Constructor for PhoneNumber
      *
      * @param string $phoneNumber The phone number for the tag
      */
-    public function __construct($phoneNumber) {
+    public function __construct(string $phoneNumber) {
         $this->phoneNumber = $phoneNumber;
     }
 
@@ -27,7 +77,7 @@ public function __construct($phoneNumber) {
      *
      * @param string $username The username for http authentication on the audio url
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -36,7 +86,7 @@ public function username($username) {
      *
      * @param string $password The password for http authentication on the audio url
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -45,7 +95,7 @@ public function password($password) {
      *
      * @param string $transferAnswerUrl The url to receive the transfer answered callback 
      */
-    public function transferAnswerUrl($transferAnswerUrl) {
+    public function transferAnswerUrl(string $transferAnswerUrl) {
         $this->transferAnswerUrl = $transferAnswerUrl;
     }
 
@@ -54,7 +104,7 @@ public function transferAnswerUrl($transferAnswerUrl) {
      *
      * @param string $transferAnswerMethod The http method to send the transfer answered callback 
      */
-    public function transferAnswerMethod($transferAnswerMethod) {
+    public function transferAnswerMethod(string $transferAnswerMethod) {
         $this->transferAnswerMethod = $transferAnswerMethod;
     }
 
@@ -63,7 +113,7 @@ public function transferAnswerMethod($transferAnswerMethod) {
      *
      * @param string $transferDisconnectUrl The url to receive the transfer disconnect callback 
      */
-    public function transferDisconnectUrl($transferDisconnectUrl) {
+    public function transferDisconnectUrl(string $transferDisconnectUrl) {
         $this->transferDisconnectUrl = $transferDisconnectUrl;
     }
 
@@ -72,7 +122,7 @@ public function transferDisconnectUrl($transferDisconnectUrl) {
      *
      * @param string $transferDisconnectMethod The http method to send the transfer disconnect callback 
      */
-    public function transferDisconnectMethod($transferDisconnectMethod) {
+    public function transferDisconnectMethod(string $transferDisconnectMethod) {
         $this->transferDisconnectMethod = $transferDisconnectMethod;
     }
 
@@ -81,7 +131,7 @@ public function transferDisconnectMethod($transferDisconnectMethod) {
      *
      * @param string $tag A custom string to be included in callbacks 
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
@@ -90,7 +140,7 @@ public function tag($tag) {
      *
      * @param string $transferAnswerFallbackUrl Fallback URL for transfer answer events 
      */
-    public function transferAnswerFallbackUrl($transferAnswerFallbackUrl) {
+    public function transferAnswerFallbackUrl(string $transferAnswerFallbackUrl) {
         $this->transferAnswerFallbackUrl = $transferAnswerFallbackUrl;
     }
 
@@ -99,7 +149,7 @@ public function transferAnswerFallbackUrl($transferAnswerFallbackUrl) {
      *
      * @param string $transferAnswerFallbackMethod HTTP method for fallback events 
      */
-    public function transferAnswerFallbackMethod($transferAnswerFallbackMethod) {
+    public function transferAnswerFallbackMethod(string $transferAnswerFallbackMethod) {
         $this->transferAnswerFallbackMethod = $transferAnswerFallbackMethod;
     }
 
@@ -108,7 +158,7 @@ public function transferAnswerFallbackMethod($transferAnswerFallbackMethod) {
      *
      * @param string $fallbackUsername HTTP basic auth username for fallback events 
      */
-    public function fallbackUsername($fallbackUsername) {
+    public function fallbackUsername(string $fallbackUsername) {
         $this->fallbackUsername = $fallbackUsername;
     }
 
@@ -117,11 +167,11 @@ public function fallbackUsername($fallbackUsername) {
      *
      * @param string $fallbackPassword HTTP basic auth password for fallback events
      */
-    public function fallbackPassword($fallbackPassword) {
+    public function fallbackPassword(string $fallbackPassword) {
         $this->fallbackPassword = $fallbackPassword;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("PhoneNumber");
 
         $element->appendChild($doc->createTextNode($this->phoneNumber));
diff --git a/src/Voice/Bxml/PlayAudio.php b/src/Voice/Bxml/PlayAudio.php
index a642516..5409f4b 100644
--- a/src/Voice/Bxml/PlayAudio.php
+++ b/src/Voice/Bxml/PlayAudio.php
@@ -9,16 +9,30 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class PlayAudio extends Verb {
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
+    /**
+     * @var string
+     */
+    private $url;
 
     /**
      * Constructor for PlayAudio
      *
      * @param string $url The URL of the audio to be played
      */
-    public function __construct($url) {
+    public function __construct(string $url) {
         $this->url = $url;
     }
 
@@ -27,7 +41,7 @@ public function __construct($url) {
      *
      * @param string $username The username for http authentication on the audio url
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -36,11 +50,11 @@ public function username($username) {
      *
      * @param string $password The password for http authentication on the audio url
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("PlayAudio");
 
         $element->appendChild($doc->createTextNode($this->url));
diff --git a/src/Voice/Bxml/Record.php b/src/Voice/Bxml/Record.php
index 3ce965a..57e83a8 100644
--- a/src/Voice/Bxml/Record.php
+++ b/src/Voice/Bxml/Record.php
@@ -9,16 +9,90 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Record extends Verb {
+    /**
+     * @var string
+     */
+    private $fallbackPassword;
+    /**
+     * @var string
+     */
+    private $fallbackUsername;
+    /**
+     * @var string
+     */
+    private $recordCompleteFallbackMethod;
+    /**
+     * @var string
+     */
+    private $recordCompleteFallbackUrl;
+    /**
+     * @var int
+     */
+    private $silenceTimeout;
+    /**
+     * @var string
+     */
+    private $transcriptionAvailableMethod;
+    /**
+     * @var string
+     */
+    private $transcriptionAvailableUrl;
+    /**
+     * @var bool
+     */
+    private $transcribe;
+    /**
+     * @var string
+     */
+    private $fileFormat;
+    /**
+     * @var int
+     */
+    private $maxDuration;
+    /**
+     * @var string
+     */
+    private $terminatingDigits;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
+    /**
+     * @var string
+     */
+    private $recordingAvailableMethod;
+    /**
+     * @var string
+     */
+    private $recordingAvailableUrl;
+    /**
+     * @var string
+     */
+    private $recordCompleteMethod;
+    /**
+     * @var string
+     */
+    private $recordCompleteUrl;
+    /**
+     * @var string
+     */
+    private $tag;
 
     /**
      * Sets the tag attribute for Record
      *
      * @param string $tag A custom string to be included in callbacks
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
@@ -27,7 +101,7 @@ public function tag($tag) {
      *
      * @param string $recordCompleteUrl URL to send the record complete callback to
      */
-    public function recordCompleteUrl($recordCompleteUrl) {
+    public function recordCompleteUrl(string $recordCompleteUrl) {
         $this->recordCompleteUrl = $recordCompleteUrl;
     }
 
@@ -37,7 +111,7 @@ public function recordCompleteUrl($recordCompleteUrl) {
      * @param string $recordCompleteMethod HTTP method to send record complete
      * as ("GET" or "POST")
      */
-    public function recordCompleteMethod($recordCompleteMethod) {
+    public function recordCompleteMethod(string $recordCompleteMethod) {
         $this->recordCompleteMethod = $recordCompleteMethod;
     }
 
@@ -46,7 +120,7 @@ public function recordCompleteMethod($recordCompleteMethod) {
      *
      * @param string $recordingAvailableUrl URL to send the record available callback to
      */
-    public function recordingAvailableUrl($recordingAvailableUrl) {
+    public function recordingAvailableUrl(string $recordingAvailableUrl) {
         $this->recordingAvailableUrl = $recordingAvailableUrl;
     }
 
@@ -56,7 +130,7 @@ public function recordingAvailableUrl($recordingAvailableUrl) {
      * @param string $recordingAvailableMethod HTTP method to send record available
      * as ("GET" or "POST")
      */
-    public function recordingAvailableMethod($recordingAvailableMethod) {
+    public function recordingAvailableMethod(string $recordingAvailableMethod) {
         $this->recordingAvailableMethod = $recordingAvailableMethod;
     }
 
@@ -65,7 +139,7 @@ public function recordingAvailableMethod($recordingAvailableMethod) {
      *
      * @param string $username Username for basic auth for callbacks
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -74,7 +148,7 @@ public function username($username) {
      *
      * @param string $password Password for basic auth for callbacks
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -83,7 +157,7 @@ public function password($password) {
      *
      * @param string $terminatingDigits Digits to terminate the recording
      */
-    public function terminatingDigits($terminatingDigits) {
+    public function terminatingDigits(string $terminatingDigits) {
         $this->terminatingDigits = $terminatingDigits;
     }
 
@@ -92,7 +166,7 @@ public function terminatingDigits($terminatingDigits) {
      *
      * @param int $maxDuration Maximum length of the recording in secods
      */
-    public function maxDuration($maxDuration) {
+    public function maxDuration(int $maxDuration) {
         $this->maxDuration = $maxDuration;
     }
 
@@ -101,7 +175,7 @@ public function maxDuration($maxDuration) {
      *
      * @param string $fileFormat Audio format of the recording ("mp3" or "wav")
      */
-    public function fileFormat($fileFormat) {
+    public function fileFormat(string $fileFormat) {
         $this->fileFormat = $fileFormat;
     }
 
@@ -119,7 +193,7 @@ public function detectLanguage($detectLanguage) {
      *
      * @param boolean $transcribe True to submit the recording for transcription, false otherwise
      */
-    public function transcribe($transcribe) {
+    public function transcribe(bool $transcribe) {
         $this->transcribe = $transcribe;
     }
 
@@ -128,7 +202,7 @@ public function transcribe($transcribe) {
      *
      * @param string $transcriptionAvailableUrl URL to send transcription available events to
      */
-    public function transcriptionAvailableUrl($transcriptionAvailableUrl) {
+    public function transcriptionAvailableUrl(string $transcriptionAvailableUrl) {
         $this->transcriptionAvailableUrl = $transcriptionAvailableUrl;
     }
 
@@ -137,7 +211,7 @@ public function transcriptionAvailableUrl($transcriptionAvailableUrl) {
      *
      * @param string $transcriptionAvailableMethod HTTP method (GET or POST) to send the transcription available event as
      */
-    public function transcriptionAvailableMethod($transcriptionAvailableMethod) {
+    public function transcriptionAvailableMethod(string $transcriptionAvailableMethod) {
         $this->transcriptionAvailableMethod = $transcriptionAvailableMethod;
     }
 
@@ -146,7 +220,7 @@ public function transcriptionAvailableMethod($transcriptionAvailableMethod) {
      *
      * @param int $silenceTimeout Number of seconds of silence that ends the recording
      */
-    public function silenceTimeout($silenceTimeout) {
+    public function silenceTimeout(int $silenceTimeout) {
         $this->silenceTimeout = $silenceTimeout;
     }
 
@@ -155,7 +229,7 @@ public function silenceTimeout($silenceTimeout) {
      *
      * @param string $recordCompleteFallbackUrl Fallback URL for record complete events 
      */
-    public function recordCompleteFallbackUrl($recordCompleteFallbackUrl) {
+    public function recordCompleteFallbackUrl(string $recordCompleteFallbackUrl) {
         $this->recordCompleteFallbackUrl = $recordCompleteFallbackUrl;
     }
 
@@ -164,7 +238,7 @@ public function recordCompleteFallbackUrl($recordCompleteFallbackUrl) {
      *
      * @param string $recordCompleteFallbackMethod HTTP method for fallback events 
      */
-    public function recordCompleteFallbackMethod($recordCompleteFallbackMethod) {
+    public function recordCompleteFallbackMethod(string $recordCompleteFallbackMethod) {
         $this->recordCompleteFallbackMethod = $recordCompleteFallbackMethod;
     }
 
@@ -173,7 +247,7 @@ public function recordCompleteFallbackMethod($recordCompleteFallbackMethod) {
      *
      * @param string $fallbackUsername HTTP basic auth username for fallback events 
      */
-    public function fallbackUsername($fallbackUsername) {
+    public function fallbackUsername(string $fallbackUsername) {
         $this->fallbackUsername = $fallbackUsername;
     }
 
@@ -182,11 +256,11 @@ public function fallbackUsername($fallbackUsername) {
      *
      * @param string $fallbackPassword HTTP basic auth password for fallback events 
      */
-    public function fallbackPassword($fallbackPassword) {
+    public function fallbackPassword(string $fallbackPassword) {
         $this->fallbackPassword = $fallbackPassword;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Record");
 
         if(isset($this->tag)) {
diff --git a/src/Voice/Bxml/Redirect.php b/src/Voice/Bxml/Redirect.php
index 95dc16e..8968831 100644
--- a/src/Voice/Bxml/Redirect.php
+++ b/src/Voice/Bxml/Redirect.php
@@ -9,16 +9,54 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Redirect extends Verb {
+    /**
+     * @var string
+     */
+    private $fallbackPassword;
+    /**
+     * @var string
+     */
+    private $fallbackUsername;
+    /**
+     * @var string
+     */
+    private $redirectFallbackMethod;
+    /**
+     * @var string
+     */
+    private $redirectFallbackUrl;
+    /**
+     * @var string
+     */
+    private $tag;
+    /**
+     * @var string
+     */
+    private $redirectMethod;
+    /**
+     * @var string
+     */
+    private $redirectUrl;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
 
     /**
      * Sets the username attribute for Redirect
      *
      * @param string $username The username for http authentication on the redirect callback url
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -27,7 +65,7 @@ public function username($username) {
      *
      * @param string $password The password for http authentication on the redirect callback url
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -36,7 +74,7 @@ public function password($password) {
      *
      * @param string $redirectUrl The url to receive the redirect callback 
      */
-    public function redirectUrl($redirectUrl) {
+    public function redirectUrl(string $redirectUrl) {
         $this->redirectUrl = $redirectUrl;
     }
 
@@ -45,7 +83,7 @@ public function redirectUrl($redirectUrl) {
      *
      * @param string $redirectMethod The http method to send the redirect callback 
      */
-    public function redirectMethod($redirectMethod) {
+    public function redirectMethod(string $redirectMethod) {
         $this->redirectMethod = $redirectMethod;
     }
 
@@ -54,7 +92,7 @@ public function redirectMethod($redirectMethod) {
      *
      * @param string $tag A custom string to be included in callbacks 
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
@@ -63,7 +101,7 @@ public function tag($tag) {
      *
      * @param string $redirectFallbackUrl Fallback url for redirect events 
      */
-    public function redirectFallbackUrl($redirectFallbackUrl) {
+    public function redirectFallbackUrl(string $redirectFallbackUrl) {
         $this->redirectFallbackUrl = $redirectFallbackUrl;
     }
 
@@ -72,7 +110,7 @@ public function redirectFallbackUrl($redirectFallbackUrl) {
      *
      * @param string $redirectFallbackMethod HTTP method for fallback events 
      */
-    public function redirectFallbackMethod($redirectFallbackMethod) {
+    public function redirectFallbackMethod(string $redirectFallbackMethod) {
         $this->redirectFallbackMethod = $redirectFallbackMethod;
     }
 
@@ -81,7 +119,7 @@ public function redirectFallbackMethod($redirectFallbackMethod) {
      *
      * @param string $fallbackUsername HTTP basic auth username for fallback events
      */
-    public function fallbackUsername($fallbackUsername) {
+    public function fallbackUsername(string $fallbackUsername) {
         $this->fallbackUsername = $fallbackUsername;
     }
 
@@ -90,11 +128,11 @@ public function fallbackUsername($fallbackUsername) {
      *
      * @param string $fallbackPassword HTTP basic auth password for fallback events 
      */
-    public function fallbackPassword($fallbackPassword) {
+    public function fallbackPassword(string $fallbackPassword) {
         $this->fallbackPassword = $fallbackPassword;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Redirect");
 
         if(isset($this->username)) {
diff --git a/src/Voice/Bxml/Response.php b/src/Voice/Bxml/Response.php
index ed24d75..3734809 100644
--- a/src/Voice/Bxml/Response.php
+++ b/src/Voice/Bxml/Response.php
@@ -12,6 +12,10 @@
 use DOMDocument;
 
 class Response {
+    /**
+     * @var array
+     */
+    private $verbs;
 
     /**
      * Creates the Response class with an emty list of verbs
@@ -25,7 +29,7 @@ public function __construct() {
      *
      * @param Verb $verb The verb to add to the list
      */
-    public function addVerb($verb) {
+    public function addVerb(Verb $verb) {
         array_push($this->verbs, $verb);
     }
 
diff --git a/src/Voice/Bxml/ResumeRecording.php b/src/Voice/Bxml/ResumeRecording.php
index 89400d2..f3537fd 100644
--- a/src/Voice/Bxml/ResumeRecording.php
+++ b/src/Voice/Bxml/ResumeRecording.php
@@ -9,11 +9,13 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class ResumeRecording extends Verb {
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("ResumeRecording");
         return $element;
     }
diff --git a/src/Voice/Bxml/Ring.php b/src/Voice/Bxml/Ring.php
index 01bc62d..fd90307 100644
--- a/src/Voice/Bxml/Ring.php
+++ b/src/Voice/Bxml/Ring.php
@@ -9,16 +9,26 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Ring extends Verb {
+    /**
+     * @var bool
+     */
+    private $answerCall;
+    /**
+     * @var float
+     */
+    private $duration;
 
     /**
      * Sets the duration attribute for Ring
      *
      * @param float $duration The duration in seconds for the ring
      */
-    public function duration($duration) {
+    public function duration(float $duration) {
         $this->duration = $duration;
     }
 
@@ -27,11 +37,11 @@ public function duration($duration) {
      *
      * @param boolean $answerCall Determines whether or not to answer the call when Ring is executed on an unanswered incoming call
      */
-    public function answerCall($answerCall) {
+    public function answerCall(bool $answerCall) {
         $this->answerCall = $answerCall;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Ring");
 
         if(isset($this->duration)) {
diff --git a/src/Voice/Bxml/SendDtmf.php b/src/Voice/Bxml/SendDtmf.php
index 819fcee..4682a72 100644
--- a/src/Voice/Bxml/SendDtmf.php
+++ b/src/Voice/Bxml/SendDtmf.php
@@ -9,16 +9,30 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class SendDtmf extends Verb {
+    /**
+     * @var float
+     */
+    private $toneInterval;
+    /**
+     * @var float
+     */
+    private $toneDuration;
+    /**
+     * @var string
+     */
+    private $digits;
 
     /**
      * Constructor for SendDtmf
      *
      * @param string $digits The dtmf digits
      */
-    public function __construct($digits) {
+    public function __construct(string $digits) {
         $this->digits = $digits;
     }
 
@@ -27,7 +41,7 @@ public function __construct($digits) {
      *
      * @param double $toneDuration The length in milliseconds of each DTMF tone
      */
-    public function toneDuration($toneDuration) {
+    public function toneDuration(float $toneDuration) {
         $this->toneDuration = $toneDuration;
     }
 
@@ -36,11 +50,11 @@ public function toneDuration($toneDuration) {
      *
      * @param double $toneInterval The duration of silence in milliseconds following each DTMF tone
      */
-    public function toneInterval($toneInterval) {
+    public function toneInterval(float $toneInterval) {
         $this->toneInterval = $toneInterval;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("SendDtmf");
 
         $element->appendChild($doc->createTextNode($this->digits));
diff --git a/src/Voice/Bxml/SipUri.php b/src/Voice/Bxml/SipUri.php
index f3f9f3b..6e019de 100644
--- a/src/Voice/Bxml/SipUri.php
+++ b/src/Voice/Bxml/SipUri.php
@@ -9,16 +9,70 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class SipUri extends Verb {
+    /**
+     * @var string
+     */
+    private $fallbackPassword;
+    /**
+     * @var string
+     */
+    private $fallbackUsername;
+    /**
+     * @var string
+     */
+    private $transferAnswerFallbackMethod;
+    /**
+     * @var string
+     */
+    private $transferAnswerFallbackUrl;
+    /**
+     * @var string
+     */
+    private $uui;
+    /**
+     * @var string
+     */
+    private $tag;
+    /**
+     * @var string
+     */
+    private $transferDisconnectMethod;
+    /**
+     * @var string
+     */
+    private $transferDisconnectUrl;
+    /**
+     * @var string
+     */
+    private $transferAnswerMethod;
+    /**
+     * @var string
+     */
+    private $transferAnswerUrl;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
+    /**
+     * @var string
+     */
+    private $sip;
 
     /**
      * Constructor for SipUri
      *
      * @param string $sip The sip uri destination 
      */
-    public function __construct($sip) {
+    public function __construct(string $sip) {
         $this->sip = $sip;
     }
 
@@ -27,7 +81,7 @@ public function __construct($sip) {
      *
      * @param string $username The username for http authentication on the audio url
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -36,7 +90,7 @@ public function username($username) {
      *
      * @param string $password The password for http authentication on the audio url
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -45,7 +99,7 @@ public function password($password) {
      *
      * @param string $transferAnswerUrl The url to receive the transfer answered callback 
      */
-    public function transferAnswerUrl($transferAnswerUrl) {
+    public function transferAnswerUrl(string $transferAnswerUrl) {
         $this->transferAnswerUrl = $transferAnswerUrl;
     }
 
@@ -54,7 +108,7 @@ public function transferAnswerUrl($transferAnswerUrl) {
      *
      * @param string $transferAnswerMethod The http method to send the transfer answered callback 
      */
-    public function transferAnswerMethod($transferAnswerMethod) {
+    public function transferAnswerMethod(string $transferAnswerMethod) {
         $this->transferAnswerMethod = $transferAnswerMethod;
     }
 
@@ -63,7 +117,7 @@ public function transferAnswerMethod($transferAnswerMethod) {
      *
      * @param string $transferDisconnectUrl The url to receive the transfer disconnect callback 
      */
-    public function transferDisconnectUrl($transferDisconnectUrl) {
+    public function transferDisconnectUrl(string $transferDisconnectUrl) {
         $this->transferDisconnectUrl = $transferDisconnectUrl;
     }
 
@@ -72,7 +126,7 @@ public function transferDisconnectUrl($transferDisconnectUrl) {
      *
      * @param string $transferDisconnectMethod The http method to send the transfer disconnect callback 
      */
-    public function transferDisconnectMethod($transferDisconnectMethod) {
+    public function transferDisconnectMethod(string $transferDisconnectMethod) {
         $this->transferDisconnectMethod = $transferDisconnectMethod;
     }
 
@@ -81,7 +135,7 @@ public function transferDisconnectMethod($transferDisconnectMethod) {
      *
      * @param string $tag A custom string to be included in callbacks 
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
@@ -90,7 +144,7 @@ public function tag($tag) {
      *
      * @param string $uui The value of the `User-To-User` header to send within the initial `INVITE`
      */
-    public function uui($uui) {
+    public function uui(string $uui) {
         $this->uui = $uui;
     }
 
@@ -99,7 +153,7 @@ public function uui($uui) {
      *
      * @param string $transferAnswerFallbackUrl Fallback URL for transfer answer events 
      */
-    public function transferAnswerFallbackUrl($transferAnswerFallbackUrl) {
+    public function transferAnswerFallbackUrl(string $transferAnswerFallbackUrl) {
         $this->transferAnswerFallbackUrl = $transferAnswerFallbackUrl;
     }
 
@@ -108,7 +162,7 @@ public function transferAnswerFallbackUrl($transferAnswerFallbackUrl) {
      *
      * @param string $transferAnswerFallbackMethod HTTP method for fallback events 
      */
-    public function transferAnswerFallbackMethod($transferAnswerFallbackMethod) {
+    public function transferAnswerFallbackMethod(string $transferAnswerFallbackMethod) {
         $this->transferAnswerFallbackMethod = $transferAnswerFallbackMethod;
     }
 
@@ -117,7 +171,7 @@ public function transferAnswerFallbackMethod($transferAnswerFallbackMethod) {
      *
      * @param string $fallbackUsername HTTP basic auth username for fallback events 
      */
-    public function fallbackUsername($fallbackUsername) {
+    public function fallbackUsername(string $fallbackUsername) {
         $this->fallbackUsername = $fallbackUsername;
     }
 
@@ -126,11 +180,11 @@ public function fallbackUsername($fallbackUsername) {
      *
      * @param string $fallbackPassword HTTP basic auth password for fallback events
      */
-    public function fallbackPassword($fallbackPassword) {
+    public function fallbackPassword(string $fallbackPassword) {
         $this->fallbackPassword = $fallbackPassword;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("SipUri");
 
         $element->appendChild($doc->createTextNode($this->sip));
diff --git a/src/Voice/Bxml/SpeakSentence.php b/src/Voice/Bxml/SpeakSentence.php
index 68e3dcb..7e25e62 100644
--- a/src/Voice/Bxml/SpeakSentence.php
+++ b/src/Voice/Bxml/SpeakSentence.php
@@ -9,16 +9,34 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class SpeakSentence extends Verb {
+    /**
+     * @var string
+     */
+    private $gender;
+    /**
+     * @var string
+     */
+    private $locale;
+    /**
+     * @var string
+     */
+    private $voice;
+    /**
+     * @var string
+     */
+    private $sentence;
 
     /**
      * Constructor for SpeakSentence
      *
      * @param string $sentence The sentence to speak in the call
      */
-    public function __construct($sentence) {
+    public function __construct(string $sentence) {
         $this->sentence = $sentence;
     }
 
@@ -27,7 +45,7 @@ public function __construct($sentence) {
      *
      * @param string $voice The voice to speak in the call
      */
-    public function voice($voice) {
+    public function voice(string $voice) {
         $this->voice = $voice;
     }
 
@@ -36,7 +54,7 @@ public function voice($voice) {
      *
      * @param string $locale The locale of the voice in the call
      */
-    public function locale($locale) {
+    public function locale(string $locale) {
         $this->locale = $locale;
     }
 
@@ -45,11 +63,11 @@ public function locale($locale) {
      *
      * @param string $gender The gender of the voice in the call
      */
-    public function gender($gender) {
+    public function gender(string $gender) {
         $this->gender = $gender;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("SpeakSentence");
 
         $element->appendChild($doc->createTextNode($this->sentence));
diff --git a/src/Voice/Bxml/StartGather.php b/src/Voice/Bxml/StartGather.php
index 5778346..cf9469b 100644
--- a/src/Voice/Bxml/StartGather.php
+++ b/src/Voice/Bxml/StartGather.php
@@ -9,18 +9,40 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 require_once "SpeakSentence.php";
 require_once "PlayAudio.php";
 
 class StartGather extends Verb {
+    /**
+     * @var string
+     */
+    private $tag;
+    /**
+     * @var string
+     */
+    private $dtmfMethod;
+    /**
+     * @var string
+     */
+    private $dtmfUrl;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
 
     /**
      * Sets the username attribute for StartGather
      *
      * @param string $username The username for http authentication for the gather callback
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -29,7 +51,7 @@ public function username($username) {
      *
      * @param string $password The password for http authentication for the gather callback
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -38,7 +60,7 @@ public function password($password) {
      *
      * @param string $dtmfUrl The url to receive the dtmf callback 
      */
-    public function dtmfUrl($dtmfUrl) {
+    public function dtmfUrl(string $dtmfUrl) {
         $this->dtmfUrl = $dtmfUrl;
     }
 
@@ -47,7 +69,7 @@ public function dtmfUrl($dtmfUrl) {
      *
      * @param string $dtmfMethod The http method to send the dtmf callback 
      */
-    public function dtmfMethod($dtmfMethod) {
+    public function dtmfMethod(string $dtmfMethod) {
         $this->dtmfMethod = $dtmfMethod;
     }
 
@@ -56,11 +78,11 @@ public function dtmfMethod($dtmfMethod) {
      *
      * @param string $tag A custom string to be included in callbacks 
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("StartGather");
 
         if(isset($this->username)) {
diff --git a/src/Voice/Bxml/StartRecording.php b/src/Voice/Bxml/StartRecording.php
index 76c176e..2803cb0 100644
--- a/src/Voice/Bxml/StartRecording.php
+++ b/src/Voice/Bxml/StartRecording.php
@@ -9,16 +9,58 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class StartRecording extends Verb {
+    /**
+     * @var string
+     */
+    private $transcriptionAvailableMethod;
+    /**
+     * @var string
+     */
+    private $transcriptionAvailableUrl;
+    /**
+     * @var bool
+     */
+    private $transcribe;
+    /**
+     * @var bool
+     */
+    private $multiChannel;
+    /**
+     * @var string
+     */
+    private $fileFormat;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
+    /**
+     * @var string
+     */
+    private $recordingAvailableMethod;
+    /**
+     * @var string
+     */
+    private $recordingAvailableUrl;
+    /**
+     * @var string
+     */
+    private $tag;
 
     /**
      * Sets the tag attribute for StartRecording
      *
      * @param string $tag A custom string to be included in callbacks 
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
@@ -27,7 +69,7 @@ public function tag($tag) {
      *
      * @param string $recordingAvailableUrl URL to send the record available callback to
      */
-    public function recordingAvailableUrl($recordingAvailableUrl) {
+    public function recordingAvailableUrl(string $recordingAvailableUrl) {
         $this->recordingAvailableUrl = $recordingAvailableUrl;
     }
 
@@ -37,7 +79,7 @@ public function recordingAvailableUrl($recordingAvailableUrl) {
      * @param string $recordingAvailableMethod HTTP method to send record available
      * as ("GET" or "POST")
      */
-    public function recordingAvailableMethod($recordingAvailableMethod) {
+    public function recordingAvailableMethod(string $recordingAvailableMethod) {
         $this->recordingAvailableMethod = $recordingAvailableMethod;
     }
 
@@ -46,7 +88,7 @@ public function recordingAvailableMethod($recordingAvailableMethod) {
      *
      * @param string $username Username for basic auth for callbacks
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -55,7 +97,7 @@ public function username($username) {
      *
      * @param string $password Password for basic auth for callbacks
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -64,7 +106,7 @@ public function password($password) {
      *
      * @param string $fileFormat Audio format of the recording ("mp3" or "wav")
      */
-    public function fileFormat($fileFormat) {
+    public function fileFormat(string $fileFormat) {
         $this->fileFormat = $fileFormat;
     }
 
@@ -83,7 +125,7 @@ public function detectLanguage($detectLanguage) {
      *
      * @param bool $multiChannel True to record the audio as 2 channels, false otherwise
      */
-    public function multiChannel($multiChannel) {
+    public function multiChannel(bool $multiChannel) {
         $this->multiChannel = $multiChannel;
     }
 
@@ -92,7 +134,7 @@ public function multiChannel($multiChannel) {
      *
      * @param boolean $transcribe True to submit the recording for transcription, false otherwise
      */
-    public function transcribe($transcribe) {
+    public function transcribe(bool $transcribe) {
         $this->transcribe = $transcribe;
     }
 
@@ -101,7 +143,7 @@ public function transcribe($transcribe) {
      *
      * @param string $transcriptionAvailableUrl URL to send transcription available events to
      */
-    public function transcriptionAvailableUrl($transcriptionAvailableUrl) {
+    public function transcriptionAvailableUrl(string $transcriptionAvailableUrl) {
         $this->transcriptionAvailableUrl = $transcriptionAvailableUrl;
     }
 
@@ -110,11 +152,11 @@ public function transcriptionAvailableUrl($transcriptionAvailableUrl) {
      *
      * @param string $transcriptionAvailableMethod HTTP method (GET or POST) to send the transcription available event as
      */
-    public function transcriptionAvailableMethod($transcriptionAvailableMethod) {
+    public function transcriptionAvailableMethod(string $transcriptionAvailableMethod) {
         $this->transcriptionAvailableMethod = $transcriptionAvailableMethod;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("StartRecording");
 
         if(isset($this->tag)) {
diff --git a/src/Voice/Bxml/StartStream.php b/src/Voice/Bxml/StartStream.php
index d7e1ef4..3134a11 100644
--- a/src/Voice/Bxml/StartStream.php
+++ b/src/Voice/Bxml/StartStream.php
@@ -9,16 +9,47 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class StartStream extends Verb {
+    private $streamParams;
+    /**
+     * @var bool
+     */
+    private $streamEventMethod;
+    /**
+     * @var string
+     */
+    private $streamEventUrl;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
+    /**
+     * @var string
+     */
+    private $tracks;
+    /**
+     * @var string
+     */
+    private $name;
+    /**
+     * @var string
+     */
+    private $destination;
 
     /**
      * Sets the destination attribute for StartStream
      *
      * @param string $destination A websocket URI to send the stream to. The audio from the specified tracks will be sent via websocket to this URL encoded as base64 encoded PCMU/G711 audio. See below for more details on the websocket packet format.
      */
-    public function destination($destination) {
+    public function destination(string $destination) {
         $this->destination = $destination;
     }
 
@@ -27,7 +58,7 @@ public function destination($destination) {
      *
      * @param string $name A name to refer to this stream by. Used when sending [`<StopStream>`][1]. If not provided, a random name will be generated and sent in the [`Media Stream Started`][2] webook
      */
-    public function name($name) {
+    public function name(string $name) {
         $this->name = $name;
     }
 
@@ -37,7 +68,7 @@ public function name($name) {
      * @param string $tracks The part of the call to send a stream from. `inbound`, `outbound` or `both`. Default is `inbound`. 
      * 
      */
-    public function tracks($tracks) {
+    public function tracks(string $tracks) {
         $this->tracks = $tracks;
     }
 
@@ -46,7 +77,7 @@ public function tracks($tracks) {
      *
      * @param string $username The username to send in the HTTP request to `streamEventUrl`. If specified, the URLs must be TLS-encrypted (i.e., `https`). 
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -55,7 +86,7 @@ public function username($username) {
      *
      * @param string $password The password to send in the HTTP request to `streamEventUrl`. If specified, the URLs must be TLS-encrypted (i.e., `https`).    
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -64,7 +95,7 @@ public function password($password) {
      *
      * @param string $streamEventUrl URL to send the associated Webhook events to during this stream's lifetime. Does not accept BXML. May be a relative URL. 
      */
-    public function streamEventUrl($streamEventUrl) {
+    public function streamEventUrl(string $streamEventUrl) {
         $this->streamEventUrl = $streamEventUrl;
     }
 
@@ -73,7 +104,7 @@ public function streamEventUrl($streamEventUrl) {
      *
      * @param bool $streamEventMethod The HTTP method to use for the request to `streamEventUrl`. GET or POST. Default value is POST. 
      */
-    public function streamEventMethod($streamEventMethod) {
+    public function streamEventMethod(string $streamEventMethod) {
         $this->streamEventMethod = $streamEventMethod;
     }
 
@@ -86,7 +117,7 @@ public function streamParams($streamParams) {
         $this->streamParams = $streamParams;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("StartStream");
 
         if(isset($this->destination)) {
diff --git a/src/Voice/Bxml/StopGather.php b/src/Voice/Bxml/StopGather.php
index 4de839f..3db8e82 100644
--- a/src/Voice/Bxml/StopGather.php
+++ b/src/Voice/Bxml/StopGather.php
@@ -9,11 +9,13 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class StopGather extends Verb {
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("StopGather");
         return $element;
     }
diff --git a/src/Voice/Bxml/StopRecording.php b/src/Voice/Bxml/StopRecording.php
index ac70663..f083112 100644
--- a/src/Voice/Bxml/StopRecording.php
+++ b/src/Voice/Bxml/StopRecording.php
@@ -9,11 +9,13 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class StopRecording extends Verb {
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("StopRecording");
         return $element;
     }
diff --git a/src/Voice/Bxml/StopStream.php b/src/Voice/Bxml/StopStream.php
index c6f1466..8f87240 100644
--- a/src/Voice/Bxml/StopStream.php
+++ b/src/Voice/Bxml/StopStream.php
@@ -9,20 +9,26 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class StopStream extends Verb {
+    /**
+     * @var string
+     */
+    private $name;
 
     /**
      * Sets the name attribute for StopStream
      *
-     * @param float $name (required) The name of the stream to stop. This is either the user selected name when sending the [`<StartStream>`][1] verb, or the system generated name returned in the [Media Stream Started][2] webhook if `<StartStream>` was sent with no `name` attribute.
+     * @param string $name (required) The name of the stream to stop. This is either the user selected name when sending the [`<StartStream>`][1] verb, or the system generated name returned in the [Media Stream Started][2] webhook if `<StartStream>` was sent with no `name` attribute.
      */
-    public function name($name) {
+    public function name(string $name) {
         $this->name = $name;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("StopStream");
 
         if(isset($this->name)) {
diff --git a/src/Voice/Bxml/StreamParam.php b/src/Voice/Bxml/StreamParam.php
index cafff17..6775829 100644
--- a/src/Voice/Bxml/StreamParam.php
+++ b/src/Voice/Bxml/StreamParam.php
@@ -9,16 +9,26 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class StreamParam extends Verb {
+    /**
+     * @var string
+     */
+    private $value;
+    /**
+     * @var string
+     */
+    private $name;
 
     /**
      * Sets the name attribute for StreamParam
      *
      * @param string $name (required) The name of this parameter, up to 256 characters.
      */
-    public function name($name) {
+    public function name(string $name) {
         $this->name = $name;
     }
 
@@ -27,11 +37,11 @@ public function name($name) {
      *
      * @param string $value (required) The value of this parameter, up to 2048 characters.
      */
-    public function value($value) {
+    public function value(string $value) {
         $this->value = $value;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("StreamParam");
 
         if(isset($this->name)) {
diff --git a/src/Voice/Bxml/Tag.php b/src/Voice/Bxml/Tag.php
index f72e4d7..45cf5ae 100644
--- a/src/Voice/Bxml/Tag.php
+++ b/src/Voice/Bxml/Tag.php
@@ -9,20 +9,26 @@
   
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Tag extends Verb {
+    /**
+     * @var string
+     */
+    private $tag;
 
     /**
      * Constructor for Tag
      *
      * @param string $tag The value to set the call tag to
      */
-    public function __construct($tag) {
+    public function __construct(string $tag) {
         $this->tag = $tag;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Tag");
 
         $element->appendChild($doc->createTextNode($this->tag));
diff --git a/src/Voice/Bxml/Transfer.php b/src/Voice/Bxml/Transfer.php
index 7e88621..f18a790 100644
--- a/src/Voice/Bxml/Transfer.php
+++ b/src/Voice/Bxml/Transfer.php
@@ -9,16 +9,72 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 require_once "Verb.php";
 
 class Transfer extends Verb {
+    /**
+     * @var string
+     */
+    private $fallbackPassword;
+    /**
+     * @var string
+     */
+    private $fallbackUsername;
+    /**
+     * @var string
+     */
+    private $transferCompleteFallbackMethod;
+    /**
+     * @var string
+     */
+    private $transferCompleteFallbackUrl;
+    private $sipUris;
+    private $phoneNumbers;
+    /**
+     * @var string
+     */
+    private $diversionReason;
+    /**
+     * @var string
+     */
+    private $diversionTreatment;
+    /**
+     * @var string
+     */
+    private $tag;
+    /**
+     * @var int
+     */
+    private $callTimeout;
+    /**
+     * @var string
+     */
+    private $transferCallerId;
+    /**
+     * @var string
+     */
+    private $transferCompleteMethod;
+    /**
+     * @var string
+     */
+    private $transferCompleteUrl;
+    /**
+     * @var string
+     */
+    private $password;
+    /**
+     * @var string
+     */
+    private $username;
 
     /**
      * Sets the username attribute for Transfer
      *
      * @param string $username The username for http authentication on the transfer answered callback url
      */
-    public function username($username) {
+    public function username(string $username) {
         $this->username = $username;
     }
 
@@ -27,7 +83,7 @@ public function username($username) {
      *
      * @param string $password The password for http authentication on the transfer answered callback url
      */
-    public function password($password) {
+    public function password(string $password) {
         $this->password = $password;
     }
 
@@ -36,7 +92,7 @@ public function password($password) {
      *
      * @param string $transferCompleteUrl The url to receive the transfer answered callback 
      */
-    public function transferCompleteUrl($transferCompleteUrl) {
+    public function transferCompleteUrl(string $transferCompleteUrl) {
         $this->transferCompleteUrl = $transferCompleteUrl;
     }
 
@@ -45,7 +101,7 @@ public function transferCompleteUrl($transferCompleteUrl) {
      *
      * @param string $transferCompleteMethod The http method to send the transfer answered callback 
      */
-    public function transferCompleteMethod($transferCompleteMethod) {
+    public function transferCompleteMethod(string $transferCompleteMethod) {
         $this->transferCompleteMethod = $transferCompleteMethod;
     }
 
@@ -54,7 +110,7 @@ public function transferCompleteMethod($transferCompleteMethod) {
      *
      * @param string $transferCallerId The caller id to use when the call is transferred
      */
-    public function transferCallerId($transferCallerId) {
+    public function transferCallerId(string $transferCallerId) {
         $this->transferCallerId = $transferCallerId;
     }
 
@@ -63,7 +119,7 @@ public function transferCallerId($transferCallerId) {
      *
      * @param int $callTimeout The number of seconds to wait before timing out the call
      */
-    public function callTimeout($callTimeout) {
+    public function callTimeout(int $callTimeout) {
         $this->callTimeout = $callTimeout;
     }
 
@@ -72,7 +128,7 @@ public function callTimeout($callTimeout) {
      *
      * @param string $tag A custom string to be included in callbacks 
      */
-    public function tag($tag) {
+    public function tag(string $tag) {
         $this->tag = $tag;
     }
 
@@ -81,7 +137,7 @@ public function tag($tag) {
      *
      * @param string $diversionTreatment The diversion treatment for the phone call 
      */
-    public function diversionTreatment($diversionTreatment) {
+    public function diversionTreatment(string $diversionTreatment) {
         $this->diversionTreatment = $diversionTreatment;
     }
 
@@ -90,7 +146,7 @@ public function diversionTreatment($diversionTreatment) {
      *
      * @param string $diversionReason The diversion treatment for the phone call 
      */
-    public function diversionReason($diversionReason) {
+    public function diversionReason(string $diversionReason) {
         $this->diversionReason = $diversionReason;
     }
 
@@ -117,7 +173,7 @@ public function sipUris($sipUris) {
      *
      * @param string $transferCompleteFallbackUrl Fallback url for transfer complete events 
      */
-    public function transferCompleteFallbackUrl($transferCompleteFallbackUrl) {
+    public function transferCompleteFallbackUrl(string $transferCompleteFallbackUrl) {
         $this->transferCompleteFallbackUrl = $transferCompleteFallbackUrl;
     }
 
@@ -126,7 +182,7 @@ public function transferCompleteFallbackUrl($transferCompleteFallbackUrl) {
      *
      * @param string $transferCompleteFallbackMethod HTTP method for fallback events
      */
-    public function transferCompleteFallbackMethod($transferCompleteFallbackMethod) {
+    public function transferCompleteFallbackMethod(string $transferCompleteFallbackMethod) {
         $this->transferCompleteFallbackMethod = $transferCompleteFallbackMethod;
     }
 
@@ -135,7 +191,7 @@ public function transferCompleteFallbackMethod($transferCompleteFallbackMethod)
      *
      * @param string $fallbackUsername HTTP basic auth username for fallback events 
      */
-    public function fallbackUsername($fallbackUsername) {
+    public function fallbackUsername(string $fallbackUsername) {
         $this->fallbackUsername = $fallbackUsername;
     }
 
@@ -144,11 +200,11 @@ public function fallbackUsername($fallbackUsername) {
      *
      * @param string $fallbackPassword HTTP basic auth password for fallback events
      */
-    public function fallbackPassword($fallbackPassword) {
+    public function fallbackPassword(string $fallbackPassword) {
         $this->fallbackPassword = $fallbackPassword;
     }
 
-    public function toBxml($doc) {
+    public function toBxml(DOMDocument $doc) {
         $element = $doc->createElement("Transfer");
 
         if(isset($this->username)) {
diff --git a/src/Voice/Bxml/Verb.php b/src/Voice/Bxml/Verb.php
index 7f7cde0..0d6a084 100644
--- a/src/Voice/Bxml/Verb.php
+++ b/src/Voice/Bxml/Verb.php
@@ -9,14 +9,16 @@
 
 namespace BandwidthLib\Voice\Bxml;
 
+use DOMDocument;
+
 abstract class Verb {
 
     /**
      * Converts the verb class into a DOMElement to build the complete BXML
      *
-     * @param DOMDocument $doc The document that is building the BXML
-     * @return DOMElement The element representing the verb
+//     * @param DOMDocument $doc The document that is building the BXML
+//     * @return DOMElement The element representing the verb
      */
-    abstract protected function toBxml($doc);
+    abstract protected function toBxml(DOMDocument $doc);
 
 }
diff --git a/src/Voice/Controllers/APIController.php b/src/Voice/Controllers/APIController.php
index 1afcc39..692b005 100644
--- a/src/Voice/Controllers/APIController.php
+++ b/src/Voice/Controllers/APIController.php
@@ -33,14 +33,14 @@ public function __construct($config, $httpCallBack = null)
     /**
      * Creates an outbound phone call.
      *
-     * @param string                   $accountId TODO: type description here
+     * @param string $accountId TODO: type description here
      * @param Models\CreateCallRequest $body      TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function createCall(
-        $accountId,
-        $body
+        string                   $accountId,
+        Models\CreateCallRequest $body
     ) {
 
         //prepare query string for API call
@@ -150,8 +150,8 @@ public function createCall(
      * @throws APIException Thrown if API call fails
      */
     public function getCall(
-        $accountId,
-        $callId
+        string $accountId,
+        string $callId
     ) {
 
         //prepare query string for API call
@@ -252,16 +252,16 @@ public function getCall(
 /**
      * Replaces the bxml for an active call
      *
-     * @param string                   $accountId TODO: type description here
-     * @param string                   $callId    TODO: type description here
-     * @param string                   $body      Valid BXML string 
+     * @param string $accountId TODO: type description here
+     * @param string $callId    TODO: type description here
+     * @param string $body      Valid BXML string
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function modifyCallBxml(
-        $accountId,
-        $callId,
-        $body
+        string $accountId,
+        string $callId,
+        string $body
     ) {
 
         //prepare query string for API call
@@ -360,16 +360,16 @@ public function modifyCallBxml(
     /**
      * Interrupts and replaces an active call's BXML document.
      *
-     * @param string                   $accountId TODO: type description here
-     * @param string                   $callId    TODO: type description here
+     * @param string $accountId TODO: type description here
+     * @param string $callId    TODO: type description here
      * @param Models\ModifyCallRequest $body      TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function modifyCall(
-        $accountId,
-        $callId,
-        $body
+        string                   $accountId,
+        string                   $callId,
+        Models\ModifyCallRequest $body
     ) {
 
         //prepare query string for API call
@@ -471,16 +471,16 @@ public function modifyCall(
     /**
      * Pauses or resumes a recording.
      *
-     * @param string                            $accountId TODO: type description here
-     * @param string                            $callId    TODO: type description here
+     * @param string $accountId TODO: type description here
+     * @param string $callId    TODO: type description here
      * @param Models\ModifyCallRecordingRequest $body      TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function modifyCallRecordingState(
-        $accountId,
-        $callId,
-        $body
+        string                            $accountId,
+        string                            $callId,
+        Models\ModifyCallRecordingRequest $body
     ) {
 
         //prepare query string for API call
@@ -589,8 +589,8 @@ public function modifyCallRecordingState(
      * @throws APIException Thrown if API call fails
      */
     public function getCallRecordings(
-        $accountId,
-        $callId
+        string $accountId,
+        string $callId
     ) {
 
         //prepare query string for API call
@@ -701,9 +701,9 @@ public function getCallRecordings(
      * @throws APIException Thrown if API call fails
      */
     public function getCallRecording(
-        $accountId,
-        $callId,
-        $recordingId
+        string $accountId,
+        string $callId,
+        string $recordingId
     ) {
 
         //prepare query string for API call
@@ -815,9 +815,9 @@ public function getCallRecording(
      * @throws APIException Thrown if API call fails
      */
     public function deleteRecording(
-        $accountId,
-        $callId,
-        $recordingId
+        string $accountId,
+        string $callId,
+        string $recordingId
     ) {
 
         //prepare query string for API call
@@ -923,9 +923,9 @@ public function deleteRecording(
      * @throws APIException Thrown if API call fails
      */
     public function getDownloadCallRecording(
-        $accountId,
-        $callId,
-        $recordingId
+        string $accountId,
+        string $callId,
+        string $recordingId
     ) {
 
         //prepare query string for API call
@@ -1034,9 +1034,9 @@ public function getDownloadCallRecording(
      * @throws APIException Thrown if API call fails
      */
     public function deleteRecordingMedia(
-        $accountId,
-        $callId,
-        $recordingId
+        string $accountId,
+        string $callId,
+        string $recordingId
     ) {
 
         //prepare query string for API call
@@ -1143,9 +1143,9 @@ public function deleteRecordingMedia(
      * @throws APIException Thrown if API call fails
      */
     public function getCallTranscription(
-        $accountId,
-        $callId,
-        $recordingId
+        string $accountId,
+        string $callId,
+        string $recordingId
     ) {
 
         //prepare query string for API call
@@ -1251,18 +1251,18 @@ public function getCallTranscription(
     /**
      * Requests that the specified recording be transcribed.
      *
-     * @param string                            $accountId   TODO: type description here
-     * @param string                            $callId      TODO: type description here
-     * @param string                            $recordingId TODO: type description here
+     * @param string $accountId   TODO: type description here
+     * @param string $callId      TODO: type description here
+     * @param string $recordingId TODO: type description here
      * @param Models\TranscribeRecordingRequest $body        TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function createTranscribeCallRecording(
-        $accountId,
-        $callId,
-        $recordingId,
-        $body
+        string                            $accountId,
+        string                            $callId,
+        string                            $recordingId,
+        Models\TranscribeRecordingRequest $body
     ) {
 
         //prepare query string for API call
@@ -1380,9 +1380,9 @@ public function createTranscribeCallRecording(
      * @throws APIException Thrown if API call fails
      */
     public function deleteCallTranscription(
-        $accountId,
-        $callId,
-        $recordingId
+        string $accountId,
+        string $callId,
+        string $recordingId
     ) {
 
         //prepare query string for API call
@@ -1482,22 +1482,22 @@ public function deleteCallTranscription(
     /**
      * Returns information about the conferences in the account.
      *
-     * @param string  $accountId      TODO: type description here
-     * @param string  $name           (optional) TODO: type description here
-     * @param string  $minCreatedTime (optional) TODO: type description here
-     * @param string  $maxCreatedTime (optional) TODO: type description here
+     * @param string $accountId      TODO: type description here
+     * @param string|null $name           (optional) TODO: type description here
+     * @param string|null $minCreatedTime (optional) TODO: type description here
+     * @param string|null $maxCreatedTime (optional) TODO: type description here
      * @param integer $pageSize       (optional) Example: 1000
-     * @param string  $pageToken      (optional) TODO: type description here
+     * @param string|null $pageToken      (optional) TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function getConferences(
-        $accountId,
-        $name = null,
-        $minCreatedTime = null,
-        $maxCreatedTime = null,
-        $pageSize = 1000,
-        $pageToken = null
+        string $accountId,
+        string $name = null,
+        string $minCreatedTime = null,
+        string $maxCreatedTime = null,
+        int    $pageSize = 1000,
+        string $pageToken = null
     ) {
 
         //prepare query string for API call
@@ -1612,8 +1612,8 @@ public function getConferences(
      * @throws APIException Thrown if API call fails
      */
     public function getConference(
-        $accountId,
-        $conferenceId
+        string $accountId,
+        string $conferenceId
     ) {
 
         //prepare query string for API call
@@ -1714,16 +1714,16 @@ public function getConference(
     /**
      * Modify the conference state.
      *
-     * @param string                         $accountId    TODO: type description here
-     * @param string                         $conferenceId TODO: type description here
+     * @param string $accountId    TODO: type description here
+     * @param string $conferenceId TODO: type description here
      * @param Models\ModifyConferenceRequest $body         TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function modifyConference(
-        $accountId,
-        $conferenceId,
-        $body
+        string                         $accountId,
+        string                         $conferenceId,
+        Models\ModifyConferenceRequest $body
     ) {
 
         //prepare query string for API call
@@ -1825,18 +1825,18 @@ public function modifyConference(
     /**
      * Updates settings for a particular conference member.
      *
-     * @param string                       $accountId    TODO: type description here
-     * @param string                       $conferenceId TODO: type description here
-     * @param string                       $callId       TODO: type description here
+     * @param string $accountId    TODO: type description here
+     * @param string $conferenceId TODO: type description here
+     * @param string $callId       TODO: type description here
      * @param Models\ConferenceMemberState $body         TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function modifyConferenceMember(
-        $accountId,
-        $conferenceId,
-        $callId,
-        $body
+        string                       $accountId,
+        string                       $conferenceId,
+        string                       $callId,
+        Models\ConferenceMemberState $body
     ) {
 
         //prepare query string for API call
@@ -1946,9 +1946,9 @@ public function modifyConferenceMember(
      * @throws APIException Thrown if API call fails
      */
     public function getConferenceMember(
-        $accountId,
-        $conferenceId,
-        $memberId
+        string $accountId,
+        string $conferenceId,
+        string $memberId
     ) {
 
         //prepare query string for API call
@@ -2061,8 +2061,8 @@ public function getConferenceMember(
      * @throws APIException Thrown if API call fails
      */
     public function getConferenceRecordings(
-        $accountId,
-        $conferenceId
+        string $accountId,
+        string $conferenceId
     ) {
 
         //prepare query string for API call
@@ -2173,9 +2173,9 @@ public function getConferenceRecordings(
      * @throws APIException Thrown if API call fails
      */
     public function getConferenceRecording(
-        $accountId,
-        $conferenceId,
-        $recordingId
+        string $accountId,
+        string $conferenceId,
+        string $recordingId
     ) {
 
         //prepare query string for API call
@@ -2288,9 +2288,9 @@ public function getConferenceRecording(
      * @throws APIException Thrown if API call fails
      */
     public function getDownloadConferenceRecording(
-        $accountId,
-        $conferenceId,
-        $recordingId
+        string $accountId,
+        string $conferenceId,
+        string $recordingId
     ) {
 
         //prepare query string for API call
@@ -2395,19 +2395,19 @@ public function getDownloadConferenceRecording(
      * 1000 entries and may be empty if no recordings match the specified criteria.
      *
      * @param string $accountId    TODO: type description here
-     * @param string $from         (optional) TODO: type description here
-     * @param string $to           (optional) TODO: type description here
-     * @param string $minStartTime (optional) TODO: type description here
-     * @param string $maxStartTime (optional) TODO: type description here
+     * @param string|null $from         (optional) TODO: type description here
+     * @param string|null $to           (optional) TODO: type description here
+     * @param string|null $minStartTime (optional) TODO: type description here
+     * @param string|null $maxStartTime (optional) TODO: type description here
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function getQueryCallRecordings(
-        $accountId,
-        $from = null,
-        $to = null,
-        $minStartTime = null,
-        $maxStartTime = null
+        string $accountId,
+        string $from = null,
+        string $to = null,
+        string $minStartTime = null,
+        string $maxStartTime = null
     ) {
 
         //prepare query string for API call
diff --git a/src/Voice/Models/CallCallback.php b/src/Voice/Models/CallCallback.php
index c21f2dd..4401a50 100644
--- a/src/Voice/Models/CallCallback.php
+++ b/src/Voice/Models/CallCallback.php
@@ -235,7 +235,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['eventType']        = $this->eventType;
diff --git a/src/Voice/Models/CallRecordingMetadata.php b/src/Voice/Models/CallRecordingMetadata.php
index 139e67b..cd65992 100644
--- a/src/Voice/Models/CallRecordingMetadata.php
+++ b/src/Voice/Models/CallRecordingMetadata.php
@@ -156,7 +156,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['applicationId']    = $this->applicationId;
diff --git a/src/Voice/Models/CallState.php b/src/Voice/Models/CallState.php
index 08e2e54..6a6540e 100644
--- a/src/Voice/Models/CallState.php
+++ b/src/Voice/Models/CallState.php
@@ -162,7 +162,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['callId']          = $this->callId;
diff --git a/src/Voice/Models/ConferenceCallback.php b/src/Voice/Models/ConferenceCallback.php
index 7fab464..840f012 100644
--- a/src/Voice/Models/ConferenceCallback.php
+++ b/src/Voice/Models/ConferenceCallback.php
@@ -144,7 +144,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['conferenceId'] = $this->conferenceId;
diff --git a/src/Voice/Models/ConferenceMemberState.php b/src/Voice/Models/ConferenceMemberState.php
index 406a769..9b25767 100644
--- a/src/Voice/Models/ConferenceMemberState.php
+++ b/src/Voice/Models/ConferenceMemberState.php
@@ -66,7 +66,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['callId']         = $this->callId;
diff --git a/src/Voice/Models/ConferenceRecordingMetadata.php b/src/Voice/Models/ConferenceRecordingMetadata.php
index db38412..7277ab5 100644
--- a/src/Voice/Models/ConferenceRecordingMetadata.php
+++ b/src/Voice/Models/ConferenceRecordingMetadata.php
@@ -107,7 +107,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['accountId']    = $this->accountId;
diff --git a/src/Voice/Models/ConferenceState.php b/src/Voice/Models/ConferenceState.php
index d204467..8ef6499 100644
--- a/src/Voice/Models/ConferenceState.php
+++ b/src/Voice/Models/ConferenceState.php
@@ -84,7 +84,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['id']                    = $this->id;
diff --git a/src/Voice/Models/CreateCallRequest.php b/src/Voice/Models/CreateCallRequest.php
index c58f660..2474794 100644
--- a/src/Voice/Models/CreateCallRequest.php
+++ b/src/Voice/Models/CreateCallRequest.php
@@ -164,7 +164,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['from']                 = $this->from;
diff --git a/src/Voice/Models/CreateCallResponse.php b/src/Voice/Models/CreateCallResponse.php
index 5f11c8c..428e6ad 100644
--- a/src/Voice/Models/CreateCallResponse.php
+++ b/src/Voice/Models/CreateCallResponse.php
@@ -183,7 +183,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['accountId']            = $this->accountId;
diff --git a/src/Voice/Models/Diversion.php b/src/Voice/Models/Diversion.php
index 391d810..9026e22 100644
--- a/src/Voice/Models/Diversion.php
+++ b/src/Voice/Models/Diversion.php
@@ -52,7 +52,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['reason']  = $this->reason;
diff --git a/src/Voice/Models/MachineDetectionConfiguration.php b/src/Voice/Models/MachineDetectionConfiguration.php
index bd91b57..8745f83 100644
--- a/src/Voice/Models/MachineDetectionConfiguration.php
+++ b/src/Voice/Models/MachineDetectionConfiguration.php
@@ -140,7 +140,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['mode']                       = $this->mode;
diff --git a/src/Voice/Models/ModifyCallRecordingRequest.php b/src/Voice/Models/ModifyCallRecordingRequest.php
index 08096c7..d2a5355 100644
--- a/src/Voice/Models/ModifyCallRecordingRequest.php
+++ b/src/Voice/Models/ModifyCallRecordingRequest.php
@@ -32,7 +32,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['state'] = $this->state;
diff --git a/src/Voice/Models/ModifyCallRequest.php b/src/Voice/Models/ModifyCallRequest.php
index acd8147..9807096 100644
--- a/src/Voice/Models/ModifyCallRequest.php
+++ b/src/Voice/Models/ModifyCallRequest.php
@@ -100,7 +100,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['state']                  = $this->state;
diff --git a/src/Voice/Models/ModifyConferenceRequest.php b/src/Voice/Models/ModifyConferenceRequest.php
index bb5206a..7d9496b 100644
--- a/src/Voice/Models/ModifyConferenceRequest.php
+++ b/src/Voice/Models/ModifyConferenceRequest.php
@@ -87,7 +87,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['status']                 = $this->status;
diff --git a/src/Voice/Models/TranscribeRecordingRequest.php b/src/Voice/Models/TranscribeRecordingRequest.php
index 63bd77c..a61e140 100644
--- a/src/Voice/Models/TranscribeRecordingRequest.php
+++ b/src/Voice/Models/TranscribeRecordingRequest.php
@@ -73,7 +73,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['callbackUrl']     = $this->callbackUrl;
diff --git a/src/Voice/Models/Transcript.php b/src/Voice/Models/Transcript.php
index b162f4f..cea62f6 100644
--- a/src/Voice/Models/Transcript.php
+++ b/src/Voice/Models/Transcript.php
@@ -38,7 +38,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['text']       = $this->text;
diff --git a/src/Voice/Models/Transcription.php b/src/Voice/Models/Transcription.php
index 784c03f..84057a9 100644
--- a/src/Voice/Models/Transcription.php
+++ b/src/Voice/Models/Transcription.php
@@ -52,7 +52,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['id']            = $this->id;
diff --git a/src/Voice/Models/TranscriptionMetadata.php b/src/Voice/Models/TranscriptionMetadata.php
index 402eaf7..2026499 100644
--- a/src/Voice/Models/TranscriptionMetadata.php
+++ b/src/Voice/Models/TranscriptionMetadata.php
@@ -54,7 +54,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['id']            = $this->id;
diff --git a/src/Voice/Models/TranscriptionResponse.php b/src/Voice/Models/TranscriptionResponse.php
index 618e935..4c9334a 100644
--- a/src/Voice/Models/TranscriptionResponse.php
+++ b/src/Voice/Models/TranscriptionResponse.php
@@ -31,7 +31,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['transcripts'] = isset($this->transcripts) ?
diff --git a/src/WebRtc/Controllers/APIController.php b/src/WebRtc/Controllers/APIController.php
index 3d017aa..354e85c 100644
--- a/src/WebRtc/Controllers/APIController.php
+++ b/src/WebRtc/Controllers/APIController.php
@@ -36,14 +36,14 @@ public function __construct($config, $httpCallBack = null)
      * Participants are idempotent, so relevant parameters must be set in this function if desired.
      *
      *
-     * @param string             $accountId Account ID
-     * @param Models\Participant $body      (optional) Participant parameters
+     * @param string $accountId Account ID
+     * @param Models\Participant|null $body      (optional) Participant parameters
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function createParticipant(
-        $accountId,
-        $body = null
+        string             $accountId,
+        Models\Participant $body = null
     ) {
 
         //prepare query string for API call
@@ -126,8 +126,8 @@ public function createParticipant(
      * @throws APIException Thrown if API call fails
      */
     public function getParticipant(
-        $accountId,
-        $participantId
+        string $accountId,
+        string $participantId
     ) {
 
         //prepare query string for API call
@@ -204,8 +204,8 @@ public function getParticipant(
      * @throws APIException Thrown if API call fails
      */
     public function deleteParticipant(
-        $accountId,
-        $participantId
+        string $accountId,
+        string $participantId
     ) {
 
         //prepare query string for API call
@@ -276,14 +276,14 @@ public function deleteParticipant(
      * Sessions are idempotent, so relevant parameters must be set in this function if desired.
      *
      *
-     * @param string         $accountId Account ID
-     * @param Models\Session $body      (optional) Session parameters
+     * @param string $accountId Account ID
+     * @param Models\Session|null $body      (optional) Session parameters
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function createSession(
-        $accountId,
-        $body = null
+        string         $accountId,
+        Models\Session $body = null
     ) {
 
         //prepare query string for API call
@@ -363,8 +363,8 @@ public function createSession(
      * @throws APIException Thrown if API call fails
      */
     public function getSession(
-        $accountId,
-        $sessionId
+        string $accountId,
+        string $sessionId
     ) {
 
         //prepare query string for API call
@@ -441,8 +441,8 @@ public function getSession(
      * @throws APIException Thrown if API call fails
      */
     public function deleteSession(
-        $accountId,
-        $sessionId
+        string $accountId,
+        string $sessionId
     ) {
 
         //prepare query string for API call
@@ -516,8 +516,8 @@ public function deleteSession(
      * @throws APIException Thrown if API call fails
      */
     public function listSessionParticipants(
-        $accountId,
-        $sessionId
+        string $accountId,
+        string $sessionId
     ) {
 
         //prepare query string for API call
@@ -591,18 +591,18 @@ public function listSessionParticipants(
      * Subscriptions can optionally be provided as part of this call.
      *
      *
-     * @param string               $accountId     Account ID
-     * @param string               $sessionId     Session ID
-     * @param string               $participantId Participant ID
-     * @param Models\Subscriptions $body          (optional) Subscriptions the participant should be created with
+     * @param string $accountId     Account ID
+     * @param string $sessionId     Session ID
+     * @param string $participantId Participant ID
+     * @param Models\Subscriptions|null $body          (optional) Subscriptions the participant should be created with
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function addParticipantToSession(
-        $accountId,
-        $sessionId,
-        $participantId,
-        $body = null
+        string               $accountId,
+        string               $sessionId,
+        string               $participantId,
+        Models\Subscriptions $body = null
     ) {
 
         //prepare query string for API call
@@ -685,9 +685,9 @@ public function addParticipantToSession(
      * @throws APIException Thrown if API call fails
      */
     public function removeParticipantFromSession(
-        $accountId,
-        $sessionId,
-        $participantId
+        string $accountId,
+        string $sessionId,
+        string $participantId
     ) {
 
         //prepare query string for API call
@@ -763,9 +763,9 @@ public function removeParticipantFromSession(
      * @throws APIException Thrown if API call fails
      */
     public function getParticipantSubscriptions(
-        $accountId,
-        $sessionId,
-        $participantId
+        string $accountId,
+        string $sessionId,
+        string $participantId
     ) {
 
         //prepare query string for API call
@@ -843,18 +843,18 @@ public function getParticipantSubscriptions(
      * `Subscriptions` object to remove all subscriptions.
      *
      *
-     * @param string               $accountId     Account ID
-     * @param string               $sessionId     Session ID
-     * @param string               $participantId Participant ID
-     * @param Models\Subscriptions $body          (optional) Initial state
+     * @param string $accountId     Account ID
+     * @param string $sessionId     Session ID
+     * @param string $participantId Participant ID
+     * @param Models\Subscriptions|null $body          (optional) Initial state
      * @return ApiResponse response from the API call
      * @throws APIException Thrown if API call fails
      */
     public function updateParticipantSubscriptions(
-        $accountId,
-        $sessionId,
-        $participantId,
-        $body = null
+        string               $accountId,
+        string               $sessionId,
+        string               $participantId,
+        Models\Subscriptions $body = null
     ) {
 
         //prepare query string for API call
diff --git a/src/WebRtc/Models/AccountsParticipantsResponse.php b/src/WebRtc/Models/AccountsParticipantsResponse.php
index 50974f1..87695c1 100644
--- a/src/WebRtc/Models/AccountsParticipantsResponse.php
+++ b/src/WebRtc/Models/AccountsParticipantsResponse.php
@@ -40,7 +40,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['participant'] = $this->participant;
diff --git a/src/WebRtc/Models/Participant.php b/src/WebRtc/Models/Participant.php
index 81dda05..7aa3962 100644
--- a/src/WebRtc/Models/Participant.php
+++ b/src/WebRtc/Models/Participant.php
@@ -81,7 +81,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['id']                 = $this->id;
diff --git a/src/WebRtc/Models/ParticipantSubscription.php b/src/WebRtc/Models/ParticipantSubscription.php
index 74ba85e..8d484f8 100644
--- a/src/WebRtc/Models/ParticipantSubscription.php
+++ b/src/WebRtc/Models/ParticipantSubscription.php
@@ -32,7 +32,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['participantId'] = $this->participantId;
diff --git a/src/WebRtc/Models/Session.php b/src/WebRtc/Models/Session.php
index ba76c05..ca1a70c 100644
--- a/src/WebRtc/Models/Session.php
+++ b/src/WebRtc/Models/Session.php
@@ -38,7 +38,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['id']  = $this->id;
diff --git a/src/WebRtc/Models/Subscriptions.php b/src/WebRtc/Models/Subscriptions.php
index e57572d..499aba4 100644
--- a/src/WebRtc/Models/Subscriptions.php
+++ b/src/WebRtc/Models/Subscriptions.php
@@ -42,7 +42,7 @@ public function __construct()
     /**
      * Encode this object to JSON
      */
-    public function jsonSerialize()
+    public function jsonSerialize(): array
     {
         $json = array();
         $json['sessionId']    = $this->sessionId;
diff --git a/tests/ApiTest.php b/tests/ApiTest.php
index d8e476e..d621ee3 100644
--- a/tests/ApiTest.php
+++ b/tests/ApiTest.php
@@ -88,7 +88,7 @@ public function testCreateCallAndGetCallState() {
         $this->assertTrue(strlen($callId) > 0);
         $this->assertTrue(is_a($response->getResult()->enqueuedTime, 'DateTime'));
 
-        sleep(25);
+        sleep(20);
 
         //get phone call information
         $response = $this->bandwidthClient->getVoice()->getClient()->getCall(getenv("BW_ACCOUNT_ID"), $callId);
@@ -120,7 +120,7 @@ public function testCreateCallWithAmdAndGetCallState() {
         $callId = $response->getResult()->callId;
         $this->assertTrue(strlen($callId) > 0);
 
-        sleep(25);
+        sleep(20);
 
         //get phone call information
         $response = $this->bandwidthClient->getVoice()->getClient()->getCall(getenv("BW_ACCOUNT_ID"), $callId);