SIP ALG

[Tony_91]

Hey guys, I have a 3cx on premise on windows 10 server, I just upgraded over the weekend from v16 to v18. Before I upgraded the firewall checker passed and now that I am on v18 it shows SIP ALG is failing, the issue is that nothing has been changed or upgraded besides the 3cx. Any help would be appreciated!!!

 

[noord]

If the phones are working and audio is flowing two-way, then this is nothing to worry about.

If audio is only flowing one way, you need to DISable SIP ALG on your firewall/router. Or you can select 'PBX Delivers Audio' on the extensions, that will work around the audio-problem.

SIP ALG is a feature once designed to help with SIP behind NAT, but it causes more issues than it solves. So, it's recommended to turn if off. 3CX checks for SIP ALG and if it finds it is active, it shows that error. But that doesn't mean something isn't working, it means you MIGHT have issues and ALG MIGHT be the cause.
I suppose the way SIP ALG is detected has changed from v16 to v18 and therefore v16 didn't detect SIP ALG correctly in your case. Or the other way around, of course

 

[Tony_91]

SIP ALG is disabled in my firewall I have checked that multiple times just to be sure.

 

[JohnS_3CX]

SIP ALG failed = means it was not able to complete so the result is unknown

SIP ALG detected = means it was found on your network

This could be due to your firewall policies blocking the way the test works.
You can learn how it works here if you want to understand how the test is carried out, and relax the firewall to pass it by allowing the ip of sip-alg-detector.3cx.com through.
https://www.3cx.com/docs/firewall-checker/#h.ikh44hto4r56

 

[Tony_91]

Ok thanks JohnS_3CX! As I am getting the SIP ALG failed, sorry guys for the confusion.

 

[noord]

Okay, and what does it say then if the detection is allowed to run and ALG is not detected?
Does it say ‘not detected’ or ‘passed’ then?
I didn’t know that ‘failed’ meant it wasn’t able to detect it (eg. the detection process itself failed), tbh
But then again, I have no issues so I never bother with the firewall checker

 

[pangel]

Okay, and what does it say then if the detection is allowed to run and ALG is not detected?
Does it say ‘not detected’ or ‘passed’ then?

It says 'not detected' indeed.