[Asterisk-Users] PSTN->voip/sip echo

[JD]

I'm still relatively a novice with asterisk and am having issues with echo.
The calling party that calls a PSTN number doesnt hear the echo, but the 
answered
side via sip or forwarded to another PSTN number over voip hears 
excessive echo that
makes it difficult to communicate.

I've been playing with the zapata.conf settings for echocancel, 
echotraining, rxgain, txgain, etc
and am basically stabbing in the dark (grin)  I've read the wiki about 
it, but it doesn't go into very
much detail.

Anyone know which parameters fix this issue?
Is there an easier way than tweaking settings in zapata.conf, monitoring 
with ztmonitor, and restarting asterisk over and over?

JD