[asterisk-users] AVM Fritz BRI cards and echo cancellation

[Simon]

Hi There,

We are using 2 x AVM Fritz BRI cards with mISDN. The phones are
Linksystem SPA922's and we are getting a little echo on the lines..
from what i unserstand, these are passive cards and do not have any
onboard echo cancellation, but im wondering if there is anything that
can be done software/config wise to help with this?

I did find this (http://www.misdn.org/index.php/FAQ):

4) You set another value for tx-gain, "-1" for example to prevent
echoes. Please set the tx-gain back to "0" for those calls as in 3)
("vt0").

Can anyone comment on this please?

Thanks

Simon