2008/10/13 Tilghman Lesher <[EMAIL PROTECTED]> > <snip> > > Pray tell, how do you echo cancel in both directions? Wouldn't that > necessitate cancelling echo before it occurs on the line (sort of a white > noise/pink noise kind of operation)? Seems like modelling a projectile > such > that when it reaches its target, the atmospheric stresses during its flight > turn it into a perfect sphere (and with about the same likelihood of > success). > > -- > Tilghman > > Hi,
Thanks for replying. So, bottom line is "you can't cancel echo in both directions", right ? I read from http://lists.digium.com/pipermail/asterisk-dev/2006-January/017774.html : <http://lists.digium.com/pipermail/asterisk-dev/2006-January/017774.html> "Generally speaking there is only one direction of echo cancellation needed: towards the 4-wire (digital) party. Any echo heard by the 2-wire party is normally acoustic echo, which we don't try to alleviate." It seems it could also have been written this way : "Echo cancellation in both directions can't be done and generally speaking there is only one direction of echo cancellation needed: towards the 4-wire (digital) party. Any echo heard by the 2-wire party is normally acoustic echo, which we don't try to alleviate." Anyway, excuse me if my question seems naive but, when using a media gateway between PRI (digital) and VoIP, which are respectively the 2-wire and the 4-wire sides as both technologies use 4-wire connections ? If Alice is on the VoIP side and Bob on the ISDN/PSTN side, which one will benefit from EC ? Will Alice stop to hear echo of its own voice or Bob's voice (I've never met this case but I'm not a reference on this) ? Will Bob stop to hear echo from its own voice or Alice's voice (I've never met this case but I'm not a reference on this) ? Regards
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