[asterisk-users] background noise

[Rilawich Ango]

Hi all,

I would like to know how can I immunize the background noise in my
case.  Anyone can help?  I have adjusted txgain & rxgain in different
value but the result is the same.

ango

Below is my configuration.
asterisk1.4.21.1
zaptel1.4.11
addon1.4.7
TDM400 (FXOx4)

There is a very large background noise when a call from sip to PSTN.
Below is the test case.

A - sip phone
B - PSTN

case 1: result is normal
caller A1
callee A2

case 2: A hears B is ok but A hears much background noise from his/her
area when A say nothing.  The sound volume of A is very low when B
hears A.
caller A
callee B

case 3: same as case 2
caller B
callee A