/**
  * Send message
  * @param array $params
  * @param string $url (optional)
  * @return boolean
  */
 public static function send(array $params, $url = MESSAGE_API_URL)
 {
     $msg = new MessageAPI();
     if ($url != MESSAGE_API_URL) {
         $msg->setURL($url);
     }
     $rc = $msg->send($params);
     SingleMessageAPI::$errorMessage = $msg->getLastError();
     $msg->close();
     return $rc;
 }