Solved Suddenly trunk stopped working. Error codes 401 and 408

[TurabG]

Hi.

Until the weekend, everything was working fine. Today on Monday, SIP trunks are failing to register. At first it was all error 401 stating that provider cannot be reached;

Destination (sip:90850********@95.173.***.***:5060) is not reachable, DNS error resolving FQDN...

While the server is in fact reachable because other clients work just fine. Nevertheless I contacted the provider and they said "your client doesn't send authorization header". It is weird when 3CX says that it cannot resolve FQDN and cannot reach the SIP server while SIP server receives the connection request and returns 401.

After a couple of hours, now the error is 408 and by the provider side, nothing has changed; they still say that authorization header is empty and therefore SIP server is still returning 401 Unauthorized.

I tried changing registration type to IP rather than account based; on both the provider and 3CX; then outbound started working but inbound still doesn't work. User name and the password is definitely correct I double checked; I even changed it and tested with the new password just in case..

I ran the firewall test although nothing has changed; there is still no problem with it. It's all green. Provider IP is not blacklisted. It's even whitelisted.

How can I resolve this issue?

 

[JohnS_3CX]

@TurabG I have sent you a private message so we can take a look at your capture, please reply there.

 

[TurabG]

Thank you for your help. Turned out to be there were two bugs in the provider's software. Support staff connected to our server and checked their logs simultaneously; then they discovered the bugs and fixed it.

But still not sure why there isn't an auth header in 3CX register request. There is still a screenshot of the capture above in one of my messages. More insterestingly, it was registering in another 3CX instance despite the bugs at provider side.

 

[JohnS_3CX]

I'm glad it was all sorted in the end. We cannot guarantee everything will work without a supported provider, but it's hard to tell why the authentication didn't take place without looking at the logs and capture.