[asterisk-dev] Zaptel Echo Cancellation

[Chan Kwang Mien]

Hi,

My test-bed is as follows :

Caller <--> PSTN Simulator <--> Asterisk <--> Callee

The PSTN Simulator is from VConsole and it simulates echo with a delay = 
50ms. Asterisk PBX is
equipped with Digium TE400P Card.

I realised that Echo can still be heard at the Callee whether the Zaptel 
MG2 Echo Cancellation is turned on or off.
However, when the rx gain value = -5 and tx gain value = 0, the echo 
becomes barely audible.

Am I right that Zaptel Echo Cancellation is suitable only to cancel certain 
type of echo ?
Does anyone have any comments on this ?

regards,
Kwang Mien