Call fails immediately - no packets leave the PBX.

[SweetAction]

Hello,
When using a support SIP trunk - calls work no issue.
When using an unsupported SIP Trunk, I can get calls no issue. However I am unable to make calls.
I've done some troubleshooting with the vendor and we ran into an interesting issue. They only accept calls over Secure SIP (5061).
When I have the trunk configured for transport mode: any I can see the packets leaving the PBX, leaving the network, and they see it hit their edge device (with a contact of IP:5060 which they don't accept). However, when I set transport mode to TLS and upload their root cert, the call fails right away. I don't see the call leaving the PBX or my network - a simple ip filter in wireshark for their IP comes up blank - and I'm a little stuck on how to proceed. The 3CX logs show the call (attached below) though.

Any ideas?

 

[YiannisH_3CX]

Hi @SweetAction

Is your provider IP based or registration based? Here is a guide we have on how TLS works in 3CX and some steps to troubleshoot it if necessary: https://www.3cx.com/docs/sip-trunk-tls-srtp/
My guess is that the TLS handshake fails when trying to initiate a call and that is why nothing is leaving the PBX but that is just a guess.

 

[SweetAction]

Hi @YiannisH_3CX
That's a great document. It's an IP based trunk and the provider only gave an IP not an FQDN. I've asked them for updated information and will keep this thread updated with an findings.

 

[SweetAction]

@YiannisH_3CX

With a FQDN I get this:


What does Error 499 mean in 3CX? I don't know I've seen this response code before. I understand the 503 - no transports left to try, but trying to understand what happened to the 1 transport/IP it did have.

 

[YiannisH_3CX]

Without being able to see the entire log I cannot really say what caused the error but the original error seems to be the 503 Transport failure.
The 500 server error with the 499 description is the translation of the error sent back to whatever device attempted the call so the error you should be trying to fix is the 503.