[asterisk-users] echo over digital line

[Kevin P. Fleming]

Vieri wrote:

> According to this article:
> http://www.audiodesignline.com/howto/206800151;jsessionid=UJRLVDJCJT2QMQSNDLPSKHSCJUNN2JVN?pgno=1
> I (on the Asterisk system) should take care of the remote user's echo issue, ie. either my BRI card or my Asterisk add-on software should correctly echo cancel.

No, that is not correct. The echo cancellers used in
Zaptel/DAHDI/mISDN/etc. (software or hardware) are used to cancel the
echo generated by the far end of the near end party's voice. In your
example, any echo of your own voice (input via your SIP phone and sent
out over the ISDN network) generated by the remote analog PSTN line
would be cancelled so that you would not hear it.

It is not possible to cancel echo that the far end party hears, it must
be cancelled as near as possible to the device hearing the echo.

-- 
Kevin P. Fleming
Director of Software Technologies
Digium, Inc. - "The Genuine Asterisk Experience" (TM)