No audio on some extension

[biomas]

Hello,
we're experiencing a weird problem: we have a SIP trunk, connected to a digital receptionist that forward calls to a ring group in case the caller doesn't make a choice. When the extension in that particular group answer the call they very often (90% of the times), don't hear the caller, the caller on the other hand hears perfectly.

• 3CX v16 is completely updated, PBX is currently handling audio, but unchecking the option doesn't solve the problem
• Audio on internal call is always ok
• I've added a different extension to the same group and I could not reproduce the problem, audio is always ok in both directions
• I've used the working extension as a model to check every setting in the problematic extensions, they are absolutely identical (in particular I've checked the codecs)
• I've reproduced the problem using the Android client (before that I had already updated the phones to the last firmware, reverted to an older firmware, reset and reprovisioned the phone; physical phones are all Yealink, same model, same firmware)

Do you have any suggestion?
Thanks!

 

[ChrisC_3CX]

3CX v16 is completely updated

First off, do bear in mind that the latest stable build of 3CX is v18. Where is the PBX hosted (cloud,on-prem) and on what OS?

Audio on internal call is always ok

What SIP Trunk are you using, is it from a 3CX Supported provider?

I've reproduced the problem using the Android client

So have you provisioned a completely different extension to this Android device and could not reproduce the problem? Have you tried deleting and re-creating a problematic extension, does that fix the issue?

Might not be related in the end since this happens on the android app too but, how are the IP Phones provisioned(STUN,SBC or Local)?

 

[biomas]

Thanks Chris,
I'll update the server to 3CX to v18 ASAP.
The provider is unfortunately not supported.

I've provisioned the problematic extension to an Android device and reproduced the problem.

Phones are local.

 

[ChrisC_3CX]

I've provisioned the problematic extension to an Android device and reproduced the problem.

Can you try deleting and recreating the extension and then reprovision so that we can confirm if the issue is related to extension configuration or not?

 

[biomas]

Already done that.

Can you try deleting and recreating the extension and then reprovision so that we can confirm if the issue is related to extension configuration or not?

Already done that :-(

 

[ChrisC_3CX]

Already done that :-(

And the issue persists? If yes, it would suggest that the issue is not extension related.

If that's the case, there's a very simple test you can try for narrowing down audio issues. Make sure the affected extension is configured to record all calls. Then, reproduce the issue and check the recording file. If you cannot hear the caller's audio on their either, it would probably mean that the PBX is not receiving the audio either in which case you might have to reach out to the SIP Provider.

If you want to troubleshoot this even further and get rid of any doubts, you can check out our academy's troubleshooting course for more info on how to do this using tools like wireshark: https://www.3cx.com/3cxacademy/videos/advanced/basic-troubleshooting/