### Answer --- When migrating to a new Retell workspace, you need to re-import your Twilio numbers and reconfigure the SIP trunk connection—there's no automatic transfer of settings between workspaces. Steps to set up Twilio SIP Trunking on your new workspace: 1. Verify your Twilio Elastic SIP Trunk configuration: - Ensure termination (outbound) is set up with the correct termination SIP URI [(1) ]() - Ensure origination (inbound) points to Retell's SIP server:

sip:sip.retellai.com

- Confirm your numbers are moved to the elastic SIP trunk in Twilio 2. Import numbers to Retell: - Import each number to your new Retell workspace with the termination SIP URI - If using credential-based auth, supply the username and password - You can import via the dashboard or the [Import Number API]() 3. Common issues to check: For outbound "invalid destination" errors: - Remove any spaces in your Termination SIP URI - Use a localized termination URI near your region - Verify username/password credentials match exactly (username differs from friendly name) - If you have "Secure Trunking" enabled in Twilio, try turning it off [(2) ]() For **inbound calls not answered**: - Confirm origination URI is set to

sip:sip.retellai.com

[(1) ]() - Ensure the imported number is bound to an agent in Retell 4. IP Whitelisting (if needed) : Retell's IP blocks:

18.98.16.120/30

(All regions) ,

143.223.88.0/21

(US only) ,

161.115.160.0/19

(US only) [(3) ]() If you've verified all settings and it still doesn't work, you may want to reach out via [Contact Sales]() for wo

rkspace-specific support.

​ To learn more, see the sources I considered: [[1] Twilio](https://docs.retellai.com/deploy/twilio) [[2] Outbound Call Not Working For Twilio & Yes I’ve reviewed all the videos and Docs on this.](https://discord.com/channels/1186424376300679209/1370009438144168036) [[3] Custom Telephony Overview](https://docs.retellai.com/deploy/custom-telephony) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer --- I don't have the ability to enable features or modify workspace settings—that requires direct support from the Retell team. However, here are a few additional troubleshooting steps for the "invalid destination" error on outbound calls: Verify Termination SIP URI: - Ensure there are no spaces in the URI [(1) ]() - Use a localized termination URI near your region (not just the default) . Twilio provides region-specific URIs—check [Twilio's localized URIs documentation]() Check credentials: - The username for SIP trunk auth is not the "friendly name" shown in Twilio's credential list—verify the actual username Confirm number import details: - When importing, ensure the

termination_uri

matches exactly what you configured in Twilio (typically ends with

.pstn.twilio.com

) [(2) ]() For international dialing: - If calling outside the US, enable "Voice Geographic Permissions" under Elastic SIP Trunking in Twilio [(1) ]() Since the calls aren't reaching Twilio logs at all, the issue may be on the Retell-to-Twilio routing side. For workspace-specific enablement or account issues, please reach out via [Contact Sales]() or check [Retell AI GitHub]() for additional support channels.

​ To learn more, see the sources I considered: [[1] Twilio](https://docs.retellai.com/deploy/twilio) [[2] Import Phone Number](https://docs.retellai.com/api-references/import-phone-number) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

@AI Evy wat should be Termination SIP URI ? in twillio elastic sip trunk termination ?

### Answer --- The Termination SIP URI is the URI you configure in your Twilio Elastic SIP Trunk under the Termination section—this is used for outbound calls. [(1) ]() Key points: - The termination URI typically ends with

.pstn.twilio.com

[(2) ]() - You should use a localized termination URI near your region for better performance. You can find your localized URIs in the Twilio console. [(1) ]() - When you import the number to Retell, you supply this same termination SIP URI so Retell knows where to route outbound calls. For reference, Twilio provides region-specific termination URIs documented here: [Twilio Localized URIs]() Example format:

your-trunk-name.pstn.twilio.com

or a regional variant like

your-trunk-name.pstn.us1.twilio.com

Make sure there are no spaces in the URI when configuring.

​ To learn more, see the sources I considered: [[1] Twilio](https://docs.retellai.com/deploy/twilio) [[2] AI in SIP Calling & Telephony Solutions | Retell AI](https://www.retellai.com/blog/integrating-ai-with-sip-trunking-and-modern-telephony) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

### Answer Yes,

retell-twilliocall.pstn.twilio.com

can be your termination SIP URI, provided that's the name you gave your trunk in Twilio. [(1) ]() A few things to verify: - The format should match what you configured in Twilio's Elastic SIP Trunk termination section - Make sure there are no spaces in the URI - Consider using a localized termination URI near your region for better performance (e.g.,

retell-twilliocall.pstn.us1.twilio.com

for US) . You can view your localized URIs in the Twilio console. - When importing the number to Retell, supply this exact termination SIP URI along with username/password if you set up credential-based authentication For regional URI options, check [Twilio's localized URIs documentation]() .

​ To learn more, see the sources I considered: [[1] Twilio](https://docs.retellai.com/deploy/twilio) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.