Google voice PHP OAuth 2.0

I once used a PHP Class Library to connect to Google Voice to send SMS Text Messages. The call would work something like this:

$gv = new GoogleVoice("GmailAccount", "GmailPassword");
$gv->sms("PhoneNumber", "TextMsg");

It worked flawlessly until recently, as of 4/20/2015, Google stopped supporting old methods of logging in to Google account. So my script stopped working giving 500 error. Google says you have to use OAuth 2.0 to authenticate however I haven't found any examples online on how to accomplish this with Google Voice. The code is below, I have not written this, please let me know how to adjust the code to use Google's OAuth System.

/*
Version     0.2
License     This code is released under the MIT Open Source License. Feel     free to do whatever you want with it.
Author      lostleon@gmail.com, http://www.lostleon.com/
LastUpdate  05/28/2010


Usage:


*/

class GoogleVoice
{
    public $username;
    public $password;
    public $status;
    private $lastURL;
    private $login_auth;
    private $inboxURL = 'https://www.google.com/voice/m/';
    private $loginURL = 'https://www.google.com/accounts/ClientLogin';
    private $smsURL = 'https://www.google.com/voice/m/sendsms';

public function __construct($username, $password)
{
    $this->username = $username;
    $this->password = $password;
}

public function getLoginAuth()
{
    $login_param = "accountType=GOOGLE&Email={$this->username}&Passwd={$this->password}&service=grandcentral&source=com.lostleon.GoogleVoiceTool";
    $ch = curl_init($this->loginURL);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); 
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_USERAGENT, "Mozilla/5.0 (iPhone; U; CPU iPhone OS 2_2_1 like Mac OS X; en-us) AppleWebKit/525.18.1 (KHTML, like Gecko) Version/3.1.1 Mobile/5H11 Safari/525.20");
    curl_setopt($ch, CURLOPT_REFERER, $this->lastURL);
    curl_setopt($ch, CURLOPT_POST, "application/x-www-form-urlencoded");
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $login_param);
    $html = curl_exec($ch);
    $this->lastURL = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);
    curl_close($ch);
    $this->login_auth = $this->match('/Auth=([A-z0-9_-]+)/', $html, 1);
    return $this->login_auth;
}

public function get_rnr_se()
{
    $this->getLoginAuth();
    $ch = curl_init($this->inboxURL);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); 
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $headers = array("Authorization: GoogleLogin auth=".$this->login_auth, 'User-Agent: Mozilla/5.0 (iPhone; U; CPU iPhone OS 2_2_1 like Mac OS X; en-us) AppleWebKit/525.18.1 (KHTML, like Gecko) Version/3.1.1 Mobile/5H11 Safari/525.20');
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    $html = curl_exec($ch);
    $this->lastURL = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);
    curl_close($ch);
    $_rnr_se = $this->match('!<input.*?name="_rnr_se".*?value="(.*?)"!ms', $html, 1);
    return $_rnr_se;
}

public function sms($to_phonenumber, $smstxt)
{
    $_rnr_se = $this->get_rnr_se();
    $sms_param = "id=&c=&number=".urlencode($to_phonenumber)."&smstext=".urlencode($smstxt)."&_rnr_se=".urlencode($_rnr_se);
    $ch = curl_init($this->smsURL);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); 
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    $headers = array("Authorization: GoogleLogin auth=".$this->login_auth, 'User-Agent: Mozilla/5.0 (iPhone; U; CPU iPhone OS 2_2_1 like Mac OS X; en-us) AppleWebKit/525.18.1 (KHTML, like Gecko) Version/3.1.1 Mobile/5H11 Safari/525.20');
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_REFERER, $this->lastURL);
    curl_setopt($ch, CURLOPT_POST, true);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $sms_param);      
    $this->status = curl_exec($ch);
    $this->lastURL = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);
    curl_close($ch);
    return $this->status;
}

private function match($regex, $str, $out_ary = 0)
{
    return preg_match($regex, $str, $match) == 1 ? $match[$out_ary] : false;
}
}

I will send you to the next answer: https://stackoverflow.com/a/4131915/2992810

unfortunate google voice had changed their API so you can not use it anymore. https://github.com/aaronpk/Google-Voice-PHP-API (look at the comments in the head)

Google Voice is not an open API, so they are no maintaining it. Sorry to tell you but in my own experience today SMS services are so cheap that it will cost you less to actually buy service license than fight with Google and their constant API changes, your website can always go down because of such change. Thinks about your time as a resource, spending your time will cost you more!