On Tue, 18 Apr 2006, leonimar cape wrote: > Can someone give a suggestion on what I should do to > omit the echo. Here is may scenario > > --- h323 --- chan-ss7 --- > A---| |--------| |--------------| |----B > --- --- --- > Nextone Asterisk DMS The next version of chan_ss7 will include enabling/disabling of the zaptel echo-canceller, which probably will solve your problem. > The calling party can hear every words he/she say > after 1 to 2 seconds. But the called party can hear A > with no echo and the quality is clear. I have already > tried it in both digium (TE410P) and sangoma card > (AT104) and the results where the same. Is there any > way that I can cancel the echo? Any particular > settings that I have to change in the settings of the > asterisk? The current version of chan_ss7 does not do anything to avoid echo. It just passes the audio through the channels. The problem is when A calls an old analog phone B. Old analog phones typically bleed some of the audio back to the sender. Ordinary synchronous telephone-networks doesn't delay the audio very much ( < 10ms) so the caller will not notice any echo. Unfortunately, ip-networks induce more delay ( > 70 ms ) which will clearly sound as echo. To avoid the echo, the only (as far as I know) solution is to insert some kind of echo-canceller "in" or "to the right" of Asterisk in your drawing. As noted above, the next version of chan_ss7 will start the zaptel echo-cancellation when a new call is made (this is configurable, if you don't want echo-cancellation), and stop it again when the call is finished. Mvh. Jacob -- Jacob Tinning System Developer SIFIRA A/S
|