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Using Telnyx as a Termination Carrier for Twiliousing-telnyx-as-a-termination-carrier-for-twilio

Users with accounts in both Telnyx and Twilio portals can send calls from Twilio to Telnyx via SIP and have Telnyx terminate those calls on the PSTN.

Intro To Twilio And Telnyxintro-to-twilio-and-telnyx

The following instructions will explain how to configure both sides so that calls from Twilio are authenticated using your Telnyx SIP Connection.

In this guide we use a TwiML application as an example, but the token configuration on Twilio side will follow the same analogy for any other Twilio API based application (SDK, node, python, etc).

Telnyx Settings For Twiliotelnyx-settings-for-twilio

  1. 1Login to the Telnyx Mission Control portalTelnyx Developers.
  2. 2Click on the SIP Connections menu option and then Add SIP Connection.
  3. 3Enter a Name and select Type: IP address.
  4. 4Under Expert IP Auth Settings choose the option Token and register the suggested Token (or define any alphanumeric value that you prefer). Click Save.
  5. 5On the same connection, click + Add IP to add the following Signaling IP addresses that belong to Twilio. To do that just go to Twilio’s Networking InformationTelnyx Developers page on the portal, and see what are the Signaling IPs for your region. For example, if you are using Twilio North America Virginia those would be:
  6. 6Click on Save all Changes. Your SIP Connection should look like the image below.
  7. 7Click on the Outbound menu option and create a new Outbound Profile or use an existing one.
  8. 8Assign the new SIP Connection to the Outbound Profile to allow outbound calls to be authorized.


Your Telnyx SIP Connection is now ready to accept traffic from your Twilio account!

Twilio Settingstwilio-settings

Note: the following example uses a TwiML based application, but the same analogy and guidance for the Telnyx Token configuration is the same for any other Twilio API based application, i.e. SDK, Python, Node, etc.

  1. 9Login to the Twilio PortalTelnyx Developers.
  2. 10Have your TwiML application set in TwiML Apps tab:


  1. 11Create an TwiML application that forwards calls to Telnyx and adds a Token header like the one from this example:
  <Say>Please hold while we connect the call.</Say>
  1. 12You can trigger your application by adding it to a call flow, e.g. assigning it to a Twilio phone number and making a call to that number.
  2. 13Once the application reaches that step, Twilio will send a SIP INVITE message to Telnyx to establish the call like the one from this example.
INVITE sip:<your-to-number> SIP/2.0
Record-Route: <sip:;lr>
From: "<your-from-number>" <sip:<your-from-number>>;tag=-------------
To: <sip:<your-to-number>>
Max-Forwards: 67
Date: Wed, 16 Oct 2019 21:20:40 GMT
Min-SE: 120
X-Telnyx-Token: <your-token>
Call-ID: ------------------------
Via: SIP/2.0/UDP;branch=-------------
Via: SIP/2.0/UDP;rport=5060;received=;branch=----------------
Contact: "<your-from-number>" <sip:<your-from-number>@;transport=udp>
User-Agent: Twilio Gateway
X-Twilio-AccountSid: <your-twilio-id>
Content-Type: application/sdp
X-Twilio-CallSid: --------------
Content-Length: 238

o=root 1836844584 1836844584 IN IP4
s=Twilio Media Gateway
c=IN IP4
t=0 0
m=audio 12240 RTP/AVP 0 101
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
  1. 14Telnyx will accept that SIP INVITE and will place/redirect the call to the PSTN number placed in the SIP URI.

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