auth.php

<?php
require 'vendor/autoload.php';
header('Content-Type: application/json');

// AccountSid and AuthToken can be found in your account dashboard
$accountSid = getenv('TWILIO_ACCOUNT_SID');
$authToken = getenv('TWILIO_AUTH_TOKEN');

// The app outgoing connections will use:
$appSid = getenv('TWILIO_APP_SID');

// The client name for incoming connections:
$clientName = $_REQUEST['clientName'] ?: 'default';

// Save list registered clients sorted by most recent
$filename = 'clients.txt';
$lines = explode(",", @file_get_contents($filename));
array_unshift($lines, $clientName);
$clients = array_slice(array_unique(array_filter($lines)), 0, 10);
file_put_contents($filename, implode(",", $clients));

$capability = new Services_Twilio_Capability($accountSid, $authToken);

// This allows incoming connections as $clientName:
$capability->allowClientIncoming($clientName);

// This allows outgoing connections to $appSid with the 'From'
// parameter being the value of $clientName
$capability->allowClientOutgoing($appSid, array(), $clientName);

// This returns a token to use with Twilio based on
// the account and capabilities defined above
$token = $capability->generateToken();

echo json_encode(array('token'=>$token, 'clients'=>$clients));
?>