2008/10/10 Eric ManxPower Wieling <[EMAIL PROTECTED]> > All calls with a 2-wire analog piece have echo. You cannot perceive the > echo because it happens so fast on non-VoIP connections. On VoIP calls > you have significant extra latency while causes you you to perceive the > echo.
Do you mean "generated locally" or "generated distantly" ? I understand that VoIP extra latency sometrimes renders perceivable what was unperceivable before. What suprises me is to hear that media getways "filter one-way only" : as 2-wires analog devices produce echo, and every phone has 2-wires analog audio, in every call you've got at least 2 sources of echo : one in each endpoint. > Echo must be removed before the call is converted to VoIP -- in > your case the Media Gateway is the device that must remove echo. So, if Alice is hearing its own voice, 1. where does it most probably come from ? 2. where should it be removed ? For both, I would reply : 1. it most probably comes from Bob's phone (as other devices in-between are digital so voice can't leak from there), 2. Alice voice echo should canceled at every location: Bob's PBX, PSTN network (ISDN in the case I had in mind) and Alice's Media gateway Do you agree ? > > > Olivier wrote: > > Hi, > > > > I'm using the following setup : > > Alice ---- IPPhone ------<LAN>----- Media gateway ----<PSTN> ------- > Phone > > ---- Bob > > > > For certain calls, users complains about echo : they can ear their own > voice > > in their handset, though media gateway echo cancel is turned on. > > > > I'm wondering how this echo cancelation engine is supposed to work. > > My understanding of echo is that most probably, when users complains > about > > earing their own voice, that means that distant phone or nearby equipment > is > > "leaking" : Bob's phone is sending Alice's voice signal back to Alice. > > > > So, to properly cancel, I would say Media gateway should substract from > > incoming signal the signal that left the media gateway few ms before. > > > > Discussing here and there, some say that Media Gateway never work this > way : > > it would only filters out locally generated echo. > > Do you agree with that ? > > If positive, then what can you do, if Bob's phone generate much echo ? > > > > Regards > > > > > > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > -- Bandwidth and Colocation Provided by http://www.api-digital.com -- > > > > asterisk-users mailing list > > To UNSUBSCRIBE or update options visit: > > http://lists.digium.com/mailman/listinfo/asterisk-users > > > > -- > Consulting for Asterisk, Polycom, Sangoma, Digium, Cisco, LAN, WAN, QoS, > T-1, PRI, Frame Relay, Linux, and network design. Based near > Birmingham, AL. Now accepting clients worldwide. > http://www.fnords.org/skillslist.html > > _______________________________________________ > -- Bandwidth and Colocation Provided by http://www.api-digital.com -- > > asterisk-users mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users >
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