[Asterisk-Users] EADS6550 and asterisk - echo on PSTN call

[Rich Adamson]

> 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