private function respond($smsResponse, $reservation)
 {
     $response = new TwilioTwiml();
     $response->message($smsResponse);
     if (!is_null($reservation)) {
         $response->message('Your reservation has been ' . $reservation->status . '.', ['to' => $reservation->respond_phone_number]);
     }
     return $response;
 }
<?php

// Get the PHP helper library from twilio.com/docs/php/install
// this line loads the library
require '/path/to/twilio-php/Services/Twilio.php';
$response = new Services_Twilio_Twiml();
$response->message("The Robots are coming! Head for the hills!");
print $response;
<?php

// Get the PHP helper library from twilio.com/docs/php/install
// this line loads the library
require 'Services/Twilio.php';
$response = new Services_Twilio_Twiml();
$message = $response->message();
$message->body("The Robots are coming! Head for the hills!");
$message->media("https://farm8.staticflickr.com/7090/6941316406_80b4d6d50e_z_d.jpg");
print $response;