Poor audio quality through handset but fine when using USB headset or Smartphone app?

[Neil Shaw]

Our 3CX installation has a frustrating issue where handsets intermittently have really bad audio yet USB headset users or people using the smartphone app are fine.

We have a dedicated FTTC 60:20 line for up to 8 simultaneous calls. We're running the PBX as a virtual server on a powerful host and the phones have a dedicated switch.

We've tried different handsets from two manufacturers, moved ports around on the switch, stopped the users piggybacking their LAN to PC on the phone and changed many settings on 3CX with no luck. We've tried another internet connection and replaced the switch/router.

The SIP is provided by Gamma who provide all our other SIP's.

We know this system works as it's one we have at 12 other sites.

Any ideas or help would be greatly appreciated.

TIA,
Neil

 

[Neil Shaw]

Just double-checking in case they did. We noticed some of those phones had choppy audio due to the buffer setting which has changed now in V16 to Adaptive buffer and seems to solve the issue with choppy audio which comes in after about 4 mins or so of talking and then comes and goes throughout a long conversation.

Do you have an alternate spare phone (i.e. Yealink) you can use at the same site to see if we can replicate the issue on other brands too?

It's happening on Fanvil phones they have there too. I'm guessing it's a network issue as the call recording are perfect.

 

[JohnS_3CX]

If possible, get a capture from the phone's PCAP interface during a problematic call. If it's the network, it should become more apparent from this capture and help narrow down the suspicion.

 

[Neil Shaw]

If possible, get a capture from the phone's PCAP interface during a problematic call. If it's the network, it should become more apparent from this capture and help narrow down the suspicion.

We could but because the poor calls are so random we would have to capture a huge amount of data to get some solid results. I'll see if we can capture one person for a long period.

 

[JohnS_3CX]

Yeah, that would be a good idea, especially if they plan on making a longer call ove 4-5 mins which will increase the chance to catch the issue