Why does the microsip dialer give an echo?

Question

Asterisk

Hello!
I use FreePBX distro, behind NAT, UDP.
City number via trunk from MTT (via sip).
microsip windows client.
There is no problem with sip-sip calls. There is no problem when using Linphone.
However, when calling microsip <-> mobile phone number, ONLY the person on the mobile phone can hear themselves. There is also an echo on the recording from him.
Echo cancellation enabled. Does not help.
Help, please, where to dig?

Answer 1

The person hears himself because either the microphone at your side is very sensitive or the speaker is too loud. The echo arises precisely for this reason, it is not a problem of automatic telephone exchange or provider.