Solved One way audio for incoming and outgoing calls for specific SIP trunk suddenly

[Konstantinos Theodorou]

Hello everyone,
I have been facing an issue with one SIP trunk on my 3CX server.
Starting like 10 days ago and while the line was working normally, now both on incoming and outgoing calls I can hear the other side but they can not hear me.
3CX version 18.0 update 2 (Build 314)
I also need to mention that on our 3CX we have 7 other SIP trunks that are working fine. The problem is just with this one SIP trunk, that while is not on the list of supported providers in used to work ok.
On the firewall test I get the testing port 5060... full cone test failed message, but I don't know if this message appeared even before when the line was working (received administration of the server recently).
Tried rebooting all systems as nothing was changed on the firewall or on the SIP trunk itself but there was no solution.
Any advice on the matter above would be appreciated. Just tell me what further info you might be needing from my side.
Thank you

 

[YiannisH_3CX]

Hi @Konstantinos Theodorou

The first step is to get the firewall checker to pass. Since you have other trunks that do work I don't think thats the issue but you need to cover all bases.
So here is the list of ports that need to be forwarded to your system for the firewall checker to pass.

The next step is to try placing a call to *777 from your 3CX extension and see if you can hear your voice when you speak. This is an echo test that sends your voice back to you to make sure you have 2 way audio. You can do that from a LAN extension and from a 3CX mobile client that's connected to 4G to see if you have audio going out as well.

Then you need to run a packet capture and make a test call from that provider to see if there is audio sent from the 3CX system and if it's going to the correct port requested by the provider.

Let me know if you need assistance with the last step.

 

[Konstantinos Theodorou]

Hello Yianni,

Thank you for your quick response.

Regarding what you mentioned about the ports all where already open on the firewall but I still get the same full cone test failed message.

I tried calling *777 from IP phone, desktop app and smartphone app and it is all good. It should be though as there was no problem with intercom or any of the other outgoing or incoming calls from the other SIP lines.

Probably I will need some help with the packet capture test call.

Thank you in advance

 

[YiannisH_3CX]

Probably I will need some help with the packet capture test call.

Thank you in advance

This will more likely come down to a provider issue since your other SIP Trunks work fine but we can have a look.
Before we do that though, can you tell me if this is an IP based or registration based provider? Also do you connect directly over the internet or do you have a local provider box on site?

 

[Konstantinos Theodorou]

Hello Yanni again,
SIP trunk is connected directly (register based) over internet without any box.
Let me mention also that I was two internet providers on premise and I'm routing the traffic from the one.
Do you think that maybe I should try routing it from the second to see if there is any difference?
Rest of SIP lines are routed from the second one. The SIP trunk with the issue is only routed from this internet connection.

 

[YiannisH_3CX]

I think is worth a try in case the providers modem is misbehaving for some reason. Let us know of the results.

 

[Konstantinos Theodorou]

Yep,
Provider issue after all. Changed to second internet connection and after re-registration everything got back to normal.
Problem Solved!

 

[YiannisH_3CX]

Glad to hear you were able to figure this out and thank you for the update