connection looks like:
PSTN A—> Asterisk —> SoftPhone - there is no echo
Softphone user doing transfer call and it looks now:
PSTN A —> Asterisk —> PSTN B - there is ECHO!!!
But it looks weird. User on PSTN A dont have it, but another one on PSTN B have echo with himself.
Any idea why it happen and how to fix it?