The termination SIP URI is what Twilio uses to route outbound calls from Retell AI(1). This is different from the origination URI (which handles inbound calls)(1).
Where to Find Your Termination SIP URI in Twilio:
In your Twilio Elastic SIP Trunk, go to the Termination tab(2). There you’ll create a termination SIP URI(2). The URI typically ends with .pstn.twilio.com(3).
Important Details:
- Remove any spaces - Check your termination SIP URI carefully and remove any spaces(1)
- Use a localized URI - Select a termination URI that’s geographically near your region for better performance(1). Twilio provides different regional endpoints in their localized URIs documentation(1)
- Format example - When you import your number into Retell AI, you’ll provide this termination URI(1)(4)
When You Import to Retell AI:
After setting up your Twilio SIP trunk, you need to import your phone number into Retell AI and supply this termination SIP URI during the import process(1). If you configured authentication with credentials, you’ll also need to provide the username and password(1).
You can import via the dashboard or programmatically using the Import Number API(1).
Common Issue:
Make sure you’re using the actual username from your credentials, not the “friendly name” that shows in the credential list - these are different(1).