Why is my voice stuttering in a Freebpx conference?

Question

freepbx

Welcome all. Faced a problem. Freepbx 13, voip client for android. When you collect a conference (and it is important if it is connected via wifi), then it is the subscriber with the voip client who stutters. Tried other clients - the same. But - if you switch to 3g, then everything is smooth and even. The echo test passes perfectly both on 3g and on Wifi, the call to the subscriber is also all clean.
Pings (-l 6400)
PBX client 200 ms (wifi)
PBX client 500 ms (3g)
PBX provider sip 8.9 ms.
I thought that problemma in an exchange between the client and automatic telephone exchange. But when connected via 3g, the pings are even greater but do not stutter.
Some kind of rake.

Answer 1

the key here is not pings, but jitter (and there may still be packet losses)
https://wiki.sipnet.ru/index.php/Quality_metrics...