Google Voice API Wrapper via: http://kalinchuk.com/?p=44

Google-Voice-API-Wrapper.php

<?php
// GoogleVoice(EMAIL, PASSWORD)
$gv = new GoogleVoice('example@gmail.com', 'password');
// Sends an SMS. send_sms(NUMBER, MESSAGE)
echo $gv->send_sms('+15555555555', 'Example');
// Gets all the sms
// get_sms() - returns all the sms
// get_sms(true) - returns all the unread sms
echo $gv->get_sms();
 
/**
  * Google Voice API Wrapper
  * 
  * new GoogleVoice(EMAIL, PASSWORD)
  * send_sms(NUMBER, MESSAGE)
  * get_sms()
  * get_sms(true) - unread
  *
  * @author Artem Kalinchuk
**/
 
Class GoogleVoice {
	/**
	  * Modify this
	**/
	var $account_type = 'GOOGLE'; 	// The Google account type
	var $service = 'grandcentral'; 	// Service for Google Voice is grandcentral (it may change)
	var $source = '';				// The host of your site (for logging purposes) 
	// _rnr_se - This can be found in the source code of the inbox page of your Google Voice
	// Simply view the source and search for '_rnr_se'. Should be a string of about 30
	// characters (numbers, letters, and symbols)
	var $_rnr_se = ''; 
 
	/**
	  * Do not modify
	**/
	var $url = 'https://www.google.com/';	// Google HTTPS URL
	var $auth; 								// The AUTH key
	var $email;								// Users email address
	var $password;							// Users password
 
	function __construct ($email, $password) {
		if ($email)
			$this->email = $email;
		if ($password)
			$this->password = $password;
 
		// Authenticate if the Auth key is empty
		if ($this->auth == '') {
			$this->authenticate();
		}
	}
 
	/**
	  * authenticate
	  * Authenticates using the email and password.
	  * @return Auth Session Key
	**/
 
	function authenticate () {
		$form_data = array();
		$form_data['accountType'] = $this->account_type;
		$form_data['Email'] = $this->email;
		$form_data['Passwd'] = $this->password;
		$form_data['service'] = $this->service;
		$form_data['source'] = $this->source;
 
		$response = $this->transmit($form_data, 'accounts/ClientLogin');
		preg_match("/Auth\=(.*)/", $response, $matches);
 
		if (count($matches) == 0) {
			return $response;
		} else {
			$this->auth = str_replace("Auth=", "", $matches[0]);
			return $this->auth;
		}
	}
 
	/**
	  * transmit
	  * Transmits the passed in POST data
	  * @param $form_data An array of POST fields and values
	  * @param $path The path to call
	  * @return Response from the server
	**/
 
	function transmit ($form_data, $path, $USE_POST=true) {
		$url = $this->url.$path;
		$fields = array();
 
		foreach ($form_data as $field => $value)
			$fields[] = $field.'='.urlencode($value);
 
		// POST or GET?
		if ($USE_POST) {
			$ch = curl_init($url);
			curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
			curl_setopt($ch, CURLOPT_POST, count($form_data));
			curl_setopt($ch, CURLOPT_POSTFIELDS, implode('&', $fields));
			curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
			curl_setopt($ch, CURLOPT_HTTPHEADER, array("Content-Type: application/x-www-form-urlencoded", "Authorization: GoogleLogin auth=".$this->auth));
			curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
		} else {
			$ch = curl_init($url.'?'.implode('&', $fields));
			curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
			curl_setopt($ch, CURLOPT_FOLLOWLOCATION, 1);
			curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
		}
 
		$response = curl_exec($ch);
 
		return $response;
	}
 
	/**
	  * send_sms
	  * Sends an SMS message
	  * @param $phone_number The number to send the SMS message to
	  * @param $text The message
	  * @return Response from the server (success or fail)
	**/
 
	function send_sms ($phone_number, $text) {
		$form_data = array();
		$form_data['phoneNumber'] = $phone_number;
		$form_data['text'] = $text;
		$form_data['id'] = '';
		$form_data['_rnr_se'] = $this->_rnr_se;
 
		$response = $this->transmit($form_data, 'voice/sms/send/');
 
		return $response;
	}
 
	/**
	  * get_sms
	  * Gets the HTML of the SMS inbox
	  * @param $UNREAD boolean - Show unread or not
	  * @return The HTML from the SMS inbox page
	**/
 
	function get_sms($UNREAD=false) {
		$form_data = array();
		$form_data['auth'] = $this->auth;
 
		if ($UNREAD)
			$path = 'voice/inbox/recent/unread/';
		else
			$path = 'voice/inbox/recent/';
 
		$response = $this->transmit($form_data, $path, false);
 
		return $response;
	}
}
?>