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

[Paul Cadach]

Hi,

Chan Kwang Mien wrote:
> 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.

Do you mean speakerphone (handsfree) operation of IP phone A? If so, phone A
should use its own acoustic echo canceller.

[skipped]

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

Echo cancellation works on a point connecting to analog (PSTN) part, not on IP
part, so if echocancellation isn't work properly you usually hear an echo at IP
side while analog side isn't listen echo.

> 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 ?

The problem is on your IP phone which isn't provides acoustic echo cancellation
for speakerphone or impedance balance for handset.


WBR,
Paul.