Telnyx

1. Create the trunk, select FQDN as the type, and give it a name.

2. Add FQDN Add the FQDN of Retell’s SIP server: 5t4n6j0wnrl.sip.livekit.cloud. Select SRV as the DNS record type.

3. Setup Outbound Calls Authentication

Select credentials as the authentication method, and add the username and password. You will need to use this username and password when importing the number to Retell.

4. Setup Inbound Setting

• Select +E.164 as the number format.
• Select G722, G729, OPUS as the codec.
• Select TCP as the transport method. (UDP temporarily not supported due to a connectivity issue)
• Select your SIP region.

4. Setup Outbound Setting

Create a new outbound voice profile

And select that in the outbound setting

You’ve created the elastic SIP trunk, now you would need to purchase numbers / move existing numbers to this trunk.

Now the number is set up with your elastic SIP trunking, you need to import the number to Retell so that we will know how to route the call.

Here you will supply Telnyx’s FQDN as the termination SIP URI. You can find your FQDN based on your choice of SIP region in this doc. You will also need to supply the username and password you set up earlier in the outbound authentication as well.

You can also import number programmatically via Import Number API.

Now the number is imported, you can make and receive calls with this number just like a number you purchased from Retell — it will show up in your dashboard, and you can make phone calls from Dashboard directly. You can also use the Create Phone Call API to create calls programmatically. If you wish to Retell to stop using this number, you can delete it from the dashboard or via the Delete Number API.