Using Twilio TwiML Conferencing on Telnyx with PHP

Did you know that you can create and manage conferences on Telnyx using your existing TwiML code and the Twilio SDK? And, by using Telnyx to execute your TwiML code, you'll experience better call quality at significantly lower costs.

In this 15 minute tutorial, we'll show you how to use the Telnyx Voice API voice API to create and manage conference calls with your PHP web application.

The code snippets in this guide are written using the PHP language version 5.3 or higher. We're going to use the Twilio PHP SDK to create code than can be interpreted by Telnyx, but we'll show you that later.

Ready to begin? Let's get started!

A simple conference call

 <!- A simple conference -->
<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Dial>
    <Conference>My superior Telnyx conference</Conference>
  </Dial>
</Response>

Buy and configure a phone number and connection

In the Telnyx Mission Control Portal, you can search for and buy phone numbers in countries around the world. Numbers that have voice capability can make and receive voice phone calls from just about anywhere.

Once you purchase a number, you'll need to configure that number to send a request to your web application. This callback mechanism is called a webhook. You'll need to create a connection and point that to your web application so that Telnyx can make an HTTP request when you receive a call.

Configure the connection for Call Control and select XML as the implementation type to configure Telnyx to execute your TwiML code. For the URL, enter in your current TwiML application URL. If you don't have an application URL yet, we'll create one at a later step using ngrok.

Set up your web application

Telnyx makes answering a phone call as easy as responding to an HTTP request. When a phone number you've bought through Telnyx receives an incoming call, Telnyx will send an HTTP request to your web application asking for instructions on how to handle the call. Your server will respond with an XML document containing TwiML that instructs Telnyx on what to do with the call. Those instructions can direct Telnyx to read out a message, play an MP3 file, make a recording, and much more.

To start answering phone calls, you'll need to:

• Buy and configure a Telnyx-powered phone number capable of making and receiving phone calls, link it to a connection and point it at your web application.
• Write a web application to tell Telnyx how to handle the incoming call using TwiML.
• Make your web application accessible on the Internet so Telnyx can make an HTTP request when you receive a call.

Dynamic conference calls with moderators

Now comes the fun part—writing code that will handle an incoming HTTP request from Telnyx! In this example we'll use PHP to respond to Telnyx's request and we'll use the existing Twilio (not Telnyx!) PHP SDK to generate our TwiML.

Create a moderated conference call

<?php
// Get the PHP helper library from https://twilio.com/docs/libraries/php

// this line loads the library
require_once '/path/to/vendor/autoload.php';
use Twilio\TwiML;

// Update with your own phone number in E.164 format
$CONFERENCE_MODERATOR = '+13129457420';

$response = new TwiML;

// Start with a <Dial> verb
$dial = $response->dial();

// If the caller is our CONFERENCE_MODERATOR, start conference on join and end when they leave
if ($_REQUEST['From'] == $CONFERENCE_MODERATOR) {
  $dial->conference('My superior Telnyx conference', array(
                'startConferenceOnEnter' => True,
                'endConferenceOnExit' => True
                ));
} else {
  // Else join as a regular participant
  $dial->conference('My superior Telnyx conference', array(
                'startConferenceOnEnter' => False
                ));
}

print $response;

Use the <Conference> TwiML (TeXML) noun to create a conference that begins only when a moderator joins In this example we use a couple advanced <Conference> features to allow one participant, our "moderator", to better control the call:

• startConferenceOnEnter will keep all other callers on hold until the moderator joins.
• endConferenceOnExit will cause Telnyx to end the call for everyone as soon as the moderator leaves. We use the "From" argument on Telnyx's webhook request to identify whether the current caller should be the moderator or just a regular participant.

In order for the webhooks in this code sample to work, Telnyx must be able to send your web application an HTTP request over the internet. Of course, that means your application needs to have a URL or IP address that Telnyx can reach.

In production you probably have a public URL, but you probably don't during development. That's where ngrok comes in. ngrok gives you a public URL for a local port on your development machine, which you can use to configure your Telnyx webhooks as described above.

Once ngrok is installed, you can use it at the command line to create a tunnel to whatever port your web application is running on. For example, this will create a public URL for a web application listening on port 3000.

ngrok http 3000

After executing that command, you will see that ngrok has given your application a public URL that you can use in your webhook connection configuration in the Telnyx Mission Control Portal.

Grab your ngrok public URL and head back to the connection number you configured earlier. Now let's set it to use your new ngrok URL. Don't forget to append the URL path to your actual TwiML logic! ("http://<your ngrok subdomain>.ngrok.io/voice" for example)

You're now ready to host dynamic conference calls with your PHP app. Grab some friends and give it a try!

Where to next?

We've just scratched the surface of what you can do with conference calls and your PHP application. You'll find similar guides with other languages in our developer docs or check out the full <Conference> reference documentation to complete your migration from Twilio.

Questions? Join us on our dedicated developer slack channel 24/7.