Outbound Twillio Retell not working, tried and checked many times ( Credentials, Termination url, new sub account, new number, other personal number, geographic ) getting error 403 forbidden and cause code 21 in twillio and Telephony_provider_permission_denied in retell ids call_ea7c2d0c1202efbc819fd2a280e call_791b6a67200e1aebc62d7b95d39 org_WXXT5hhzixUlfZeq Inbound is working.

I can help you troubleshoot this! The 403/cause code 21 error typically means Twilio doesn't have permission to make outbound calls to your Retell webhook URL. Most common causes: Your Retell agent's webhook URL isn't publicly accessible or is blocking Twilio's IPs Twilio account has geographic permissions restrictions for outbound calls The phone number you're calling has restrictions Quick question: Are you using any firewall, API gateway, or authentication on your Retell webhook endpoint that might be blocking Twilio's requests?

Hey @Eend You can watch this video to connect twilio

Hi, I am using SIP trunk for the calls. I am not using any webhook.

So you can confirm your termination authentication is set up correctly. Either whitelist Retell’s IP ranges in Twilio or use username/password authentication and ensure those credentials are entered exactly the same when importing the number into Retell. Also double-check the termination URI, try re-importing the number with the correct settings, and review Twilio’s logs since inbound works, this points specifically to a SIP termination configuration issue.

Since you're using SIP trunk, the issue is likely SIP trunk authentication failing for outbound calls - even though inbound works, outbound needs separate configuration Did you add the SIP trunk credentials in both Twilio's Elastic SIP Trunking settings AND in your Retell phone number configuration?

Also tried with IP ranges, but got https://cdn.discordapp.com/attachments/1458434464140234813/1458441341204693182/image.png?ex=695fa6d8&is=695e5558&hm=95a736982f36a199a89fc06c72a1c799ba719a8643531118f405ca88519e689e&

You should double-check your credentials

I did many times, copy paste it in.

Can you send me a message

I fixed it, security trunking had to be checked

Turned it on, sadly still same error 🙁

Go to your Twilio SIP Trunk settings and switch your authentication from IP Access Control to Credential Lists (using a username and password instead). Also, since you're calling the Netherlands, double-check that it's enabled in both the Low Risk and High Risk sections of your Twilio Geographic Permissions You can try this..

Tried it, Also same thing, Netherlands number not working, US is working.