asterisk users - Mar 2005 - EADS6550 and asterisk - echo on PSTN call

Hi list,

would like to know if some of you have tested asterisk connected to an 
EADS 6550 analogique PBX (also know as Nexpan50).

Our set up is a Dell Optiplex with 1 TDM400 4 FXO, 1 TDM400 4 FXS, (no 
other card, each of them have their own IRQ) all ports connected to the 
EADS. We have GS ATA286 as EP. Calling from ATA to ATA give a perfect 
sound. Calling to PSTN numbers or reverse side, give echo.

We can do what we want in zconfig.h (STEVE2, MARK2, MMX, 
AGGRESSIV_SUPPRESSOR, NOECHOCAN_DISABLE) or zapata.conf (tx gain=-10.0, 
echocancel=32 ... 256,), test with differents POTS phone, it change 
nothing. We even didn't notice changes between our various changes in 
those files (and yes modules where unloaded between each test). Always 
the same echo.

So know we start to doubt that this echo problem is asterisk related but 
perhaps more to the PBX. That's why we ask if some of you have/had 
similar setup with this PBX and if there is a solution.

Thanks for any hint.
-- 
Daniel

> would like to know if some of you have tested asterisk connected to an 
> EADS 6550 analogique PBX (also know as Nexpan50).
> 
> Our set up is a Dell Optiplex with 1 TDM400 4 FXO, 1 TDM400 4 FXS, (no 
> other card, each of them have their own IRQ) all ports connected to the 
> EADS. We have GS ATA286 as EP. Calling from ATA to ATA give a perfect 
> sound. Calling to PSTN numbers or reverse side, give echo.
> 
> We can do what we want in zconfig.h (STEVE2, MARK2, MMX, 
> AGGRESSIV_SUPPRESSOR, NOECHOCAN_DISABLE) or zapata.conf (tx gain=-10.0, 
> echocancel=32 ... 256,), test with differents POTS phone, it change 
> nothing. We even didn't notice changes between our various changes in 
> those files (and yes modules where unloaded between each test). Always 
> the same echo.
> 
> So know we start to doubt that this echo problem is asterisk related but 
> perhaps more to the PBX. That's why we ask if some of you have/had 
> similar setup with this PBX and if there is a solution.
You didn't mention what country your in; if you outside the US, be sure
to config the TDM-fxo card for your country (eg, line impedance).

You mention echocancel=32, etc, did you try echotraining=800?

For my TDM-fxo in the US, using the following on each channel works fine:

echotraining=800
echocancel=yes
echocancelwhenbridged=yes
rxgain=5.0
txgain=0.0