Solved - Bad sound quality (2024)

Hi there,
I am currently setting up my first 3CX and it's working really good so far. There is only one thing that is not so good: the overall sound quality - even with internal calls. It sounds dull and muffled because there is almost no 'S' tones (treble is very low). On the other hand, bass is also a bit low, so all in all it sounds a bit strange.
We are testing with the 3CX softphones at this point.
3CX firewall check reports that everything is fine but this only checks on the WAN side, right?
Codec priority for internal calls is G722, G729, GSM, PCMU, PCMA, OPUS. Changing codec priority in the 3CX stettings doesn't change anything it seems... that's a bit weird.
Our network never had any issues (HP ProCurve switches with loop protection), no local firewalls.

Where could I start my search?

Thanks in advance,
Bruno

What is your setup ?

3CX hosted locally or in the cloud

What phones are you using ? How are the phones provisioned - local , sbc ot stun.

You followed all the requirement for HyperV installation - https://www.3cx.com/docs/installing-microsoft-hyper-v/

I didn't consider that document when setting up the virtual guest but it's all fine:

• drivers are up to date
• VMq is disabled
• time sync is pointing to our domain controller and not to the hyperv host itself - I guess that shouldnt be a problem

Hello @Faulhaber GmbH

Make sure that the internal codecs of the PBX are also set to the same priority. You can do so by navigating to Settings / General / Codec Priority for Local/Internal Calls.
It may be a case of transcribing if PBX delivers audio is enabled on Recording is enabled under extension settings.

Thanks a lot for all your feedback. It took 4 persons to find the source of our bad sound issue:

• softphone to softphone: bad quality - that's what we were testing
• softphone to webclient: bad quality - that was our second test
• webclient to webclient: good quality - we did not check that one
• webclient to softphone: good quality - interesting because quality is bad when the softphone calls

Because we rely on TAPI and because headsets are easier to install when using softphones, we investigated further... and further. Turned out that it seems it was our mistake: we were always changing codec priorities in the general 3CX settings and suprisingly it didnt make a difference. Well, we did not know, that every phone has its own codec settings. Primary codec was GSM. As soon as we added OPUS as primary codec for each extension the sound quality changed from good to phantastic. I'm not sure if this is documented somewhere - at least I can't remember having read about this.

Again, thank you for your assistance. This forum really turns the 3CX into such a good system