Handsets use a 4-wire connection. Handsets with the the volume turned up could cause a form of echo as the microphone picks up the ear piece audio (I call this acoustic echo). Everything I said applies to 2-wire caused echo. Other types of echo is fairly uncommon and cannot be solved by normal echo canceling systems.
Most echo canceling systems I've seen (mostly tellabs) only cancel echo in one direction. I suspect all of Digium's EC systems only do echo canceling in one direction as well. Olivier wrote: > 2008/10/11 Eric ManxPower Wieling <[EMAIL PROTECTED]> > >> >> Olivier wrote: >>> 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. >> Where did you hear that media gateways "filter one-way only"? > > >>From a media gateway vendor (mentioning its own products capabilities). > That's the main reason I opened this thread as it surprised me a bit ... > >> >> Any 2-wire analog leg will be a source of echo. Many, many, many calls >> do not have a 2-wire leg. > > Even in handset audio circuit ? > I was thinking that any handset is a potential echo source due to this audio > circuit ... > Do you agree ? > -- Consulting and design services for LAN, WAN, voice and data. Based near Birmingham, AL. Now accepting clients worldwide. Contact me for Tellabs echo canceling systems. Also see 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
