asterisk users - May 2005 - YET Another echo issue PRI CARD Any help acc epted :-)

>The call always has echo on it.  The Asterisk sip extension
>hears them selves echoing.  The remote party does not notice any
>difference.
>I have also notices that the Asterisk 
>levels are very hot from T1-PRI to Sip. 
I have had good success fiddling with the txgain and rxgain values in
zapata.conf on my PRI. In my setup, cranking the gain down a LOT eliminated
most of the echo, and training the users to turn down the gain on their
handsets did the rest. It's true, with a PRI, that gains are cranked across
the board. Turning the gain down solves a lot of echo problems, with
negligible effect on voice quality. 

In zapata.conf, set txgain=-10.0 and rxgain=-10.0 and see if the echo goes
away. If it does, sucessively raise the gains by half i.e. try -5.0 / -5.0.
If the echo comes back, try half of -10 to -5 i.e -7.5/-7.5 if it doesn't,
try half of -5 to 0 i.e -2.5/-2.5. Repeat, until you find the threshold that
works for you. Restart Asterisk after every change. 

I have also noticed that SIP phones echo different. For example, X-Lite
echos a lot unless you turn down the mic and headset volume almost to the
bottom. Snom 190 echos a bit but if you turn down handset volume it goes
away. Ironically, the crappiest Grandstream BT-101 works great, perfect
audio quality if you can excuse the Wal-Mart casing, the terrible display,
and sticky buttons. 

hth

On May 26, 2005 01:58 pm, Colin Anderson wrote:
> I have had good success fiddling with the txgain and rxgain values in
> zapata.conf on my PRI. In my setup, cranking the gain down a LOT eliminated
> most of the echo, and training the users to turn down the gain on their
> handsets did the rest. It's true, with a PRI, that gains are cranked
across
> the board. Turning the gain down solves a lot of echo problems, with
> negligible effect on voice quality.
There should be *NO* reason to adjust tx/rxgain on a PRI or ANY digital 
connection!  The fact that adjusting it down 10% worked suggests that the 
telco switch is boosting the signal for some unknown reason.  Use the 
technique outlined in this message:

http://lists.digium.com/pipermail/asterisk-users/2004-November/071301.html

(It works VERY well and is very straightforward, thank you Kris, I reference 
this all the time!)

Again if you're screwing with gains on PRI you have bigger problems, I
think.

-A.