Poor sound quality 3cx gateway for skype

[Oleksandr]

Hello!

I have latest versions of 3CX gateway for skype and 3CX installed.

With both incoming and outgoing calls via Skype-gateway sound quality is awful. Strong heartbeats and clicks are audible in a voice , the sound is intermittent. Quality is improving a bit if you use an old Skype version (5 or 4).

The sound is bad only with SIP to Skype and Skype to SIP calls.
The problem apparently exsists not in the Skype but in the gateway or PBX itself or between them. If I listen to the sound during this kind of calls and connect directly to the audio card jack with my headphones, I hear perfect quality.
Also I have the audio-card replaced and it did not help.

I think, everything is configured correctly and "voice through PBX" option is seleced.

I ask for your advice, I do not know how to find the reason of this issue and how to fix it.

Thank you.

 

[leejor]

My understanding, of the operation 3CX Skype gateway, is that it uses the sound card "facilities", of the PC. Which I take it to mean that the conversations actually convert from digital, to analogue, than back to digital. It is the analogue part, that is probably causing the problem.

You say that you have replaced the audio card, but, are all other audio programmes (surround sound/multi-speaker/audio enhancement), sort of options, also removed? Given that the gateways does actually work on many installations, I have to assume (first choice) that it is something to do with the audio hardware (or their settings) on your particular computer.

 

[Oleksandr]

leejor,

Yes, I thougt about audio hardware issues first. Butat the same time (during the call) I hear perfect quality from my audiocard output.

Does anybody know where the bug might be?

PS Moderator Please move the topic to general! txs

 

[leejor]

I don't know if it was clear, how you were actually placing the calls. Are you running the 3CX phone, on the same PC running the 3CX PBX and the Skype gateway?

 

[flurk]

As a sound technician, I completely agree with the thesis of Leejor.
I am also using the 3CX gateway for skype. Sound quality is perfect on the computer running the skype gateway.
Once the signal is transferred to 3CX it is of very bad quality.
The only possible explanation that i see is that these are artifacts created by a resampling process.
I suppose (I think i once heard that...) the Skype protocol is closed source. Conversion in the digital domain is impossible. Therefor, the sound has to be converted to analog first (3CX gateway for Skype explicitly asks for a working sound device!) and it is then resampled and converted into 16bit/8kHz/mono wav for VoIP.
In such a chain of digital to analog and back to digital conversions artifacts will arise.

Besides: if you hang a speaker to the computer running the Skype gateway, you can listen in (in good quality) to the conversations running over Skype. Privacy is at stake with this specific gateway setup.
Because of this bad sound quality I have been looking for alternatives to skype and switched to another Voip-provider recently.
Cheers,
Flurk