Hello
i’ve set asterisk as the softpbx in my company and i have 2 external lines(2 FXO) and everythings goes well but when a call come from outside first the volume of the callee and the caller is little bit low so is there anyidea how can i loud the voice being transmitted on zap channel ?? 
and second when i make a call from inside asterisk 2 the outside through my zap channel there is echo and when a call came 2 me there is no echo so also is there any idea about that?
Hi,
about the volume, try playing with rxgain and taxgain, in zaptel.conf Make it abit higer and then restart *.
Echo is a hard one 
, try echocancel=yes, or else, the echo might be caused be chaep SIP phone that you might be using.
Have you tried the HPEC (High Performance Echo Canceller)?