public function send($mobileNumber, $message, $messageId = null)
    {
        return $this->sendAsync($mobileNumber, $message, $messageId)
        ->then(
            function (ResponseInterface $response) {
                return new SentResponse($response, $this->requestForm);
            },
            function ($exception) {
                return $this->throwError($exception);
            }
        )->wait();
    }