[asterisk-dev] Queries regarding Echo Cancellation in Zaptel-1.2.6

[Chan Kwang Mien]

Hi,

I conducted echo tests using zaptel-1.2.6 driver using the
following setup. 

IP Phone A <------> Asterisk IP PBX <---> Analog Phone B

I called IP Phone A using Analog Phone B. IP Phone A is answered by
someone else using its speaker. Both phones are in different rooms. 

The settings for the Echo Cancellation in zaptel are as follows :

a) Echo canceller used : ECHO_CAN_MG2 (MG2)
b) AGGRESSIVE_SUPPRESSOR is defined in zconfig.h
c) In zapata.conf :
   echocancel = yes
   echocancelwhenbridged=yes
   echotraining=yes
   echotraining=800

With and without echo cancellation in zaptel, I heard echo in Phone B.

It seems like echo cancellation cannot eradicate the echos. I was
wondering if the delay caused by traversing the one-hop IP segment of
the network too large for the echo canceller in zaptel to
handle ? 

Has anyone conducted the echo tests using the same test-setup and also
obtained the same results as mine ? 

Does anyone know if this test-setup is an appropriate setup to test the
performance of echo cancellation in zaptel ? or are there any other ways
of testing echo cancellation ?

Thank you.


Best Regards,
Kwang Mien