Audio Fading

[Alkraizer]

Greetings 3cx Forums!
I am working with a customer who is having a very strange issue, and I just can't seem to pin down the cause.
The issue is that randomly, the audio on a call fades out like someone just turns the volume button down for around 10 seconds then it comes back on and the call continues as normal. There isn't a pattern I can see for it, not a specific time that it happens more often or a specific caller that it happens to more often than others.

They have a 3cx server on site running Version 20 update 8 (build 1109)
They are all using Yealink phones
The issue happens on inbound and outbound calls
They use Flowroute as a SIP provider

Due to the random nature of the issue I haven't been able to get a pcap file that shows what might be going on, just making test calls to my DID hasn't reproduced the error.

Has anyone seen this issue before? If so, what was the cause?
I don't have any access into the client's network infrastructure so i can't say for sure what they use other than I know that they use Fortinet equipment.

Thanks in advance

 

[paulodagraca]

Hello Alkraizer,

Enable the Monitor Connection Quality for a week, and monitor the information gathered.
Also enable the call recording on a few or all phones, and use this for evaluation.
The Avtivity Log should be on Verbose, all this together should get you the answer.

Personally I would guess this is a provider problem, what SIP trunk is in use?

Paulo

 

[Kevin Attard Compagno]

Looking at this from a different angle:

If when you say "volume fading", you mean that the audio is still there, but the volume reduces significantly during the call, then:

• it means that the network packets are still being exchanged
  • a packet capture will confirm this because you will see that the audio stream is there
• it means that the codec is simply converting an audio signal/waveform that has a SMALLER AMPLITUDE (which is what lower volume is, really)
• it means that the audio volume is being lowered BEFORE the transcoding (from analog waveform to digital stream) happens (between capture device and codec processing)
• it's going to be one (or more) of:
  • user behaviour (fiddling with headset and distance between mic and mouth)
  • some automatic gain algorithm performed by the headset or the software installed by the headset
  • noise cancelling algorithms
  • ...or some variation of the above