### Answer Based on your description, here are some troubleshooting steps for your Twilio number experiencing connection issues: Check Twilio Elastic SIP Trunk Configuration: 1. Verify Termination Settings - Ensure there are no spaces in your Termination SIP URI and that you're using a localized termination URI near your region [(1) ]() . Check the Twilio console for your localized URIs . 2. Confirm IP Whitelisting - You need to whitelist Retell's SIP SBC CIDR block

18.98.16.120/30

in your Twilio trunk's termination settings . If this was accidentally removed or changed, it would cause connection failures. 3. Review Origination Settings - For inbound calls, verify your origination SIP URI is correctly set to

sip:sip.retellai.com

. Check Twilio Number Configuration: - Ensure your Twilio number is still properly assigned to your Elastic SIP Trunk . - Verify the number hasn't been moved or reassigned in Twilio. Review Retell Dashboard: - Check if the imported number still appears in your Retell dashboard with the correct agent bindings . - Verify the agent assigned to handle inbound calls is active and properly configured. Recent Service Issues: There was a brief telephony provider outage on October 28, 2025 from 11:10 AM – 11:34 AM PST that caused inbound call connection issues and timeouts [(2) ]() . If your issue occurred during this window, it may have been related to that incident, which has since been resolved . If these checks don't resolve the issue, I recommend opening a support ticket with both Twilio and Retell to review logs from both sides to identify where the call is failing.

​ To learn more, see the sources I considered: [[1] Twilio](https://docs.retellai.com/deploy/twilio) [[2] Intermittent Call Connection Failures](https://community.retellai.com/t/intermittent-call-connection-failures/143) ​

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