Hardware Echo Cancellation

Riddle me this.

I have a te412p (onboard hardware canceller) and bridge zap channels together across 4 spans connected to e1s provided by a nortel dms-100

Why is it that when I echoccancel=no in zapata.conf I get echo but when I echoccancel=yes it stops…
logically I would have thought that I wouldn’t need software echocan when using this card???

I have multiple dell 2950s each with the same behaviour so it is not a hardware fault

Can anyone enlighten me please?


asterisk 1.4.20-rc1

I am not positive, but from what i understand the ‘Echocancel’ variable completely turns on and off echo cancel.

If ‘echocancel’ is set to ‘yes’ it will use hardware cancellation if available or software if it is not.
If ‘echocancel’ is set to ‘no’ it will not use echo cancellation

One way you could test is to remove the hardware cancellation card and see if you can notice additional load on your CPU.


I have seen this around the traps that this option controlled the onboard echo can


ie by default it is always on and this option switched it off

so it is quite confusing then

Thanks for your response, will test away