Inbound call telnyx service use but not working

Getting Started
1

Hi, I am using Telnyx and I followed the documentation guidelines, but I am still getting an error. I tried debugging it but could not resolve the issue. Sharing the logs below for reference.

From the logs, it looks like Telnyx tried to start a call from +923186809417 to +12029729683 and sent the request to the LiveKit SIP server. LiveKit received the request and returned “100 Processing”, but then the call failed with “404 No trunk found.”

It seems LiveKit could not find a configured SIP trunk for the incoming call, so the call was rejected.

Logs and details are attached below. Could someone please help check what might be missing in the configuration?

1. What this log shows

This log shows a SIP phone call attempt between two systems over the internet.

• Caller:+923186809417

• Trying to call:+12029729683

• The call is sent from Telnyx SIP server to LiveKit SIP server.

2. Step-by-step what happened

Step 1 — Call request sent (INVITE)

The server 185.246.41.140 sends an INVITE message to 161.115.161.40.

This means:

:arrow_right: “I want to start a phone call to +12029729683.”

Step 2 — Server received the request (100 Processing)

The LiveKit server replies:

SIP/2.0 100 Processing

This means:

:arrow_right: “I received your request and I am processing it.”

Step 3 — Call failed (404 No trunk found)

Then the server responds:

SIP/2.0 404 No trunk found

This means:

:arrow_right: “I cannot handle this call because there is no SIP trunk configured for it.”

In simple words:

:warning: The system doesn’t know where to send this call.

Possible reasons:

• SIP trunk is not configured

• SIP trunk name/domain is wrong

• LiveKit cannot find the inbound trunk

• Authentication or routing is missing

Step 4 — Call closed (ACK)

After the error, the caller sends ACK, which means:

:arrow_right: “I received the error message and the call is now closed.”

3. Simple summary

1. Telnyx tried to start a call.

2. LiveKit received the request.

3. LiveKit could not find a SIP trunk configuration.

4. The call failed with 404 No trunk found.

4. One-line meaning

:point_right: The call failed because LiveKit could not find a configured SIP trunk for the incoming call.

2

I think the problem is that you defined the number in your trunk twice, which confuses it. You have both +12029729683 and 12029729683

Remove the one with the plus, since it will work for either a + prefix or no + prefix in bound numbers since the trunk normalizes numbers.

I was going to check our logs but I don’t actually see any inbound calls for 12029729683. I see calls in the other direction.

Do you happen to have a PCAP for the failure case? I would like to double-check that to make sure this is the issue you are having.

3

Thanks, that’s helpful.

Understood on the duplicate number point. I added the second form (12029729683) later as a troubleshooting step. Before that, we had already reproduced the
same 404 No trunk found behavior with only the +12029729683 entry on the LiveKit inbound trunk, but I agree it makes sense to simplify the trunk again and
retest with a single normalized number.

I’ll update the trunk to use only 12029729683 and retry.

Regarding the inbound calls: I do have SIP traces showing the failed inbound INVITEs reaching the LiveKit SIP endpoint and receiving 100 Processing followed
by 404 No trunk found.

Latest failing example:

  • Call-ID: 6668b86d-95a6-4827-89e2-327bf4d3d967
  • Timestamp: 2026-03-06 19:15:04 UTC
  • Request-URI: sip:+12029729683@test-voice-shu02yqv.eu.sip.livekit.cloud:5060
  • LiveKit response: 100 Processing, then 404 No trunk found

Other recent failing Call-IDs with the same behavior:

  • 46a47226-4a8f-4651-b2b4-631b459406e5
  • 4634e7cf-40aa-47b1-921c-696a375b25ff
  • 7e2f1565-5394-4d22-89cf-258a3cf46a6f

I don’t currently have a raw PCAP capture, but I can attach the full SIP trace/log export for the failing calls. If you specifically need a true PCAP rather
than the SIP trace, please let me know the preferred capture point/format and I’ll provide that.

Also, since the SIP trace clearly shows the INVITE reaching test-voice-shu02yqv.eu.sip.livekit.cloud:5060, could you please confirm whether that endpoint is
mapped to the correct project on your side and whether you can search for the above Call-IDs in your SIP backend logs?

Thanks.

4

Thanks for the callid that helped me find it and now I see why I did not see it before. The to address is not correct. You should use the SIP URL that you find here Sign in | LiveKit Cloud but looks like you are probably using the project URL instead.

5

Thanks, that makes sense.

I checked the docs as well, and I understand the SIP trunk provider should be configured with the SIP URI from LiveKit Cloud Project Settings, not the project
URL.

My current INVITEs are going to:
sip:+12029729683@test-voice-shu02yqv.eu.sip.livekit.cloud:5060

So it sounds like I may have used the project-derived host instead of the actual SIP URI/subdomain assigned to this project.

Could you please confirm the correct SIP URI (or SIP subdomain) for this project on your side? If region pinning is supported here, please also confirm
whether the correct regional endpoint format should be:
.eu.sip.livekit.cloud

Once I have the correct SIP URI/subdomain, I’ll update the Telnyx FQDN destination and retest immediately.

Thanks.

6

You will find your URI here:
https://cloud.livekit.io/projects/p_/settings/project

It will say SIP URI