Outbound agent not calling

Support Help
1

Hi Retell team,

I’m experiencing persistent telephony_provider_permission_denied errors when making outbound batch calls to Belgian numbers.

Setup Details:

  • Phone number: +32488633682

  • Provider: Custom Telnyx SIP trunk

  • Error: SIP 403 with Telnyx error code D13

  • Call status: not_connected

  • Disconnection reason: telephony_provider_permission_denied

Steps Already Taken:

  1. :white_check_mark: Added Belgium (BE) to Telnyx outbound voice profile allowed destinations

  2. :white_check_mark: Verified outbound voice profile is assigned to my SIP trunk

  3. :white_check_mark: Confirmed SIP trunk authentication credentials are correct in Retell AI

  4. :white_check_mark: Added custom SIP header X-Telnyx-Username with my username

  5. :white_check_mark: Verified account balance is sufficient

Issue:
Despite all configuration steps being completed, batch calls to Belgian numbers consistently fail with the D13 error. The calls never reach Telnyx (no logs appear on their side).

Request:
Can someone from the Retell team investigate why these calls are being rejected at the telephony provider level? Is there an account/workspace-level whitelist for Belgium that needs to be enabled?

Please let me know what additional information (call IDs, PCAP files, etc.) would be helpful for troubleshooting.

Thank you!

2

Hi @nikita.nagurniy

Can you share some call IDs and your Agent ID?

Thank You

3

Agent ID:
agent_120a5f7067584a5337fb708283

Session IDs:
call_eff0e76a2000c1c938a4fc14170
call_a8e4e5e233767509166da07c3de

Thanks for helping Shaw!

4

Hi @nikita.nagurniy

I’ve shared this with our team for review

We’ll keep you updated as soon as we have more information.

Thank You

5

Thanks for the speedy help

6

Thank you for reaching out to Retell AI Support. We’ve received your ticket and our team will respond within 8 hours.

7

Hi Retell,

Hi there,
Here are some resources to help you with your Telnyx SIP trunk integration at Retell AI:

Best,
Evy AI
AI Support Agent @ Retell AI

8

After hours analysing, claude AI gives me this:

Looking at both screenshots, I can see everything clearly:

Retell :white_check_mark: — NikitaRetell username, sip.telnyx.eu termination URI, TCP transport — all looks correct.

Telnyx :white_check_mark: — Belgium +32 is checked under Allowed Destinations.

So the problem is 100% on Retell’s account-level D13 block

Everything on both sides is configured correctly. The only thing left blocking your calls is Retell’s internal account-level country whitelist that only their support team can unlock.

9

Hi @nikita.nagurniy

I’ve reached out to our team regarding this. Once we receive an update, either I or a team member will get back to you.

Thanks for your patience!

1 Like
10

Hi @nikita.nagurniy

We’ve investigated the failing calls and can confirm that the calls are reaching your Telnyx trunk. Telnyx authenticates the SIP credentials successfully, but then rejects the call with a 403 Forbidden (D13). This means the issue is entirely on the Telnyx side, specifically their outbound destination permissions. There’s nothing to change on the Retell side, the fix needs to happen in your Telnyx portal or through Telnyx support.

Thank You

11

Thank you for your answer. I’ll get back to Telnyx

12

I checked in Telnyx. The outbound destination permissions are set to all destinations. Still, when I want to make an outbound call via Retell, it does not work.

See screenshots.

image
image1920×1243 172 KB

13

Scherm­afbeelding 2026-03-26 om 11.44.56
Scherm­afbeelding 2026-03-26 om 11.44.562230×1510 246 KB

14

Hi @nikita.nagurniy

Have you had a chance to reach out to Telnyx support regarding this? Because issue is on telnyx side

Thank You

15

My SIP Trunk Password was wrong and now I can do outbound calls, thanks for your help Shaw & team Retell!