Hi! @aizaz_jahangir It looks like the issue is on Retell’s side, since Twilio inbound calls work and Pakistan is enabled. The Designation error usually happens when Retell isn’t sending the correct SIP headers or number format that Twilio expects. Make sure the number is in E.164 format (+92XXXXXXXXXX) and double-check the SIP trunk configuration in Retell matches Twilio exactly. You can also test calling Pakistan directly from Twilio to confirm it’s allowed. Checking Retell’s debug logs can show exactly what parameter is causing the rejection.