Hi @hussain
Migration Approach:
Your plan is correct and aligns with the Twilio SIP trunking guide. The key steps are:
-
Create an elastic SIP trunk on Twilio with termination (credential auth or IP whitelisting) and origination set to
sip:sip.retellai.com -
Import the number into Retell with the termination URI and credentials
-
Southworth/Vodia re-points their outbound trunk to the new Twilio termination URI
One thing to note: if you plan outbound calls, you’ll need to whitelist Retell’s SIP SBC CIDR block 18.98.16.120/30 on the Twilio termination side, and for international dialing (Bahamas), enable the country under Twilio’s Voice Geographic Permissions → “Elastic SIP Trunking.”
Transfer Back to the Practice:
To avoid international PSTN charges on transfers back, you can set the transfer destination as a SIP URI (e.g., sip:username@domain) instead of an E.164 number. This routes the transfer over SIP directly back through the Vodia PBX rather than going out to PSTN. Both cold and warm transfers support SIP URI destinations as you can see transfer call docs. You’d configure the transfer tool’s destination as the practice’s SIP endpoint.
If SIP-based transfer isn’t feasible, the transfer would go through Twilio’s PSTN routing and international rates would apply on Twilio’s side.
Thank You