VAPI•2mo ago

telnyx

I’m having an issue with Telnyx SIP outbound calls — getting this error. I’ve followed the Telnyx SIP setup guide

A 403 Forbidden error on Telnyx SIP outbound calls usually means your SIP credentials are incorrect or not matching what's set in Telnyx. Please double-check your Vapi SIP trunk credential matches your Telnyx configuration. Here’s the format you should use:

{
  "provider": "byo-sip-trunk",
  "name": "Telnyx Trunk",
  "gateways": [{ "ip": "sip.telnyx.com", "inboundEnabled": false }],
  "outboundAuthenticationPlan": {
    "authUsername": "YOUR_SIP_USERNAME",
    "authPassword": "YOUR_SIP_PASSWORD",
    "sipRegisterPlan": { "realm": "sip.telnyx.com" }
  }
}

{
  "provider": "byo-sip-trunk",
  "name": "Telnyx Trunk",
  "gateways": [{ "ip": "sip.telnyx.com", "inboundEnabled": false }],
  "outboundAuthenticationPlan": {
    "authUsername": "YOUR_SIP_USERNAME",
    "authPassword": "YOUR_SIP_PASSWORD",
    "sipRegisterPlan": { "realm": "sip.telnyx.com" }
  }
}

Update YOUR_SIP_USERNAMEYOUR_SIP_USERNAME and YOUR_SIP_PASSWORDYOUR_SIP_PASSWORD to match your Telnyx portal exactly, then test again.
For more details, see the Vapi Telnyx SIP integration guide.

Source:

Vapi Telnyx SIP integration

⤵️ Mention @Vapi Support Bot for follow-ups 🐥

VapiAPP•11/1/25, 12:46 AM

Hi zie,

If you're looking to integrate Telnyx with Vapi, you can import your Telnyx numbers and enable outbound calling through the Telnyx Portal. Once you've configured your Telnyx account to add Vapi as a connection, you'll be ready to handle calls on the Vapi platform. Additionally, you may need to set up the SIP trunk, and you can follow this guide for detailed instructions on integrating your Telnyx SIP trunk with Vapi. This includes various setup steps such as configuring FQDN and authentication settings. Make sure to replace placeholders with your actual credentials when performing API calls.

If you need to use Telnyx as a phone number provider, detailed instructions for creating and updating phone numbers using Telnyx can be found in the API reference.

Telnyx SIP integration | Vapi

How to integrate SIP Telnyx to Vapi

broad-salmon•11/3/25, 4:42 PM

hi , I am using the same sip trunk connection for both: inbound and outbound.

therefore : ""inboundEnabled": false" -> I dont have this in the json .

but I am still getting the 403 forbidden - every other configuration looks like in the guide provided.

so what am I doing wrong here?

@Duckie

VapiAPP•11/6/25, 10:00 PM

Thanks for getting back to us and updating us We’ll share an update as soon as more information becomes available. We appreciate your understanding and patience as we continue our investigation.

VapiAPP•11/18/25, 4:28 AM

I sincerely apologize for the delayed response to your support request.
We implemented better tracking for support tickets to ensure timely responses going forward, but due to a technical limitation, this only applies to tickets created after this past week.
I'm closing this older ticket, but if your issue still needs attention, please:
Reply with 'REOPEN' or
Email support@vapi.ai with any updates
I'll personally ensure your new request gets prompt attention.
Thank you for your patience.
Best regards,
Vapi Support Team

{ "provider": "byo-sip-trunk", "name": "Telnyx Trunk", "gateways": [{ "ip": "sip.telnyx.com", "inboundEnabled": false }], "outboundAuthenticationPlan": { "authUsername": "YOUR_SIP_USERNAME", "authPassword": "YOUR_SIP_PASSWORD", "sipRegisterPlan": { "realm": "sip.telnyx.com" } } }

telnyx

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