GXW-4004 and freepbx echo what to do?

Question

Asterisk

Actually, through the GXW-4004, 3 lines are forwarded to analog phones, when you call them from ordinary ip-phones, an echo is observed from the ip phone side, and from the analog side everything is OK, where to dig?

Answer 1

Is Echo Canceller enabled in GXW-4004? jitter buffer?

Answer 2

analyze rtp, perhaps the echo appears due to the headset curve, or the included self-audible on the client side.