01. Register in twilio

Link : https://www.twilio.com/try-twilio

Register your account from above link, and fill all the details.

02. Get your authentication details

Login with your username and password,
and Go to https://www.twilio.com/console page.
1 Twilio Console
Get your ACCOUNT SID and AUTH TOKEN, this details will required in your REST API.

03. Text to Speech API

Now using IndianTTS Text to Speech API and convert your text to audio format, refer bellow code for TEXT to Speech API

<?php
 header("Access-Control-Allow-Origin: *"); 
 header("Access-Control-Allow-Credentials: true ");
 header("Access-Control-Allow-Methods: OPTIONS, GET, POST");
 header("Access-Control-Allow-Headers: Content-Type, Depth, User-Agent, X-File-Size, 
 X-Requested-With, If-Modified-Since, X-File-Name, Cache-Control");

$host = '<TTS API HOST>';
$port = '<PORT>';
$text = <TEXT>;

$url = "http://".$host.":".$port."/tts?text=".$text;

$curl = curl_init();

curl_setopt_array($curl, array(
 CURLOPT_PORT => "<PORT>",
 CURLOPT_URL => $url,
 CURLOPT_RETURNTRANSFER => true,
 CURLOPT_ENCODING => "",
 CURLOPT_MAXREDIRS => 10,
 CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
 CURLOPT_CUSTOMREQUEST => "GET",
 CURLOPT_HTTPHEADER => array(
 ),
));
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
 echo "cURL Error #:" . $err;
} else {
 echo $response;
}
?>

04. Integrate Twilio API code

Link : https://www.twilio.com/console/dev-tools/api-explorer/voice/call-create
Now using your ACCOUNT SID, AUTH TOKEN and audio URL (which is return from TTS) integrate twilio code, code screen shot is bellow

<?php
header("Access-Control-Allow-Origin: *"); 
 header("Access-Control-Allow-Credentials: true ");
 header("Access-Control-Allow-Methods: OPTIONS, GET, POST");
 header("Access-Control-Allow-Headers: Content-Type, Depth, User-Agent, X-File-Size, 
 X-Requested-With, If-Modified-Since, X-File-Name, Cache-Control");

$mobile = $_POST["mobile"];
$audio = $_POST["audio"];

require_once __DIR__ . '/twilio-php-master/Twilio/autoload.php'; // Loads the library
use Twilio\Rest\Client;

// Your Account Sid and Auth Token from twilio.com/user/account
$sid = "<Account SID>";
$token = "<Account Token>";
$client = new Client($sid, $token);

$call = $client->calls->create(
 "+91".$mobile, "<Your Mobile Number>",
 array("url" => "<Audio URL>"
);
echo $call->sid;
?>

05. Log Entry Provide by Twilio

twilio