Echo problem


#1

I hear a strong echo with analog or digital phones that generate an acoustic echo or a room echo (when speaker and microphone are switched on).
How is echo cancellation done?


#2

Here is a good artlicle on echo cancellation. This might help you out.
http://www.voip-info.org/tiki-index.php?page=Asterisk+echo+cancellation

Also, here is a link that shows you how to configure zapata.conf
http://www.voip-info.org/wiki-Asterisk+config+zapata.conf