<div dir="ltr"><br><br><div class="gmail_quote">2008/10/11 Eric ManxPower Wieling <span dir="ltr"><<a href="mailto:eric@fnords.org">eric@fnords.org</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div class="Ih2E3d"><br><snip><br>
</div>Where did you hear that media gateways "filter one-way only"?<br>
<br></blockquote><div>Hi ,<br><br>Reading over this reply, it seems to me that having EC working in one direction is not a so well known fact.<br><br>Could we say :<br>1. EC working in one direction is the general case but some of us were not aware of that (I was not, for instance)<br>
2. or this is not so widespread use and some private architectures involve EC working in both directions ?<br><br><br>For instance, what about Cisco Call Manager ?<br><br>Reading this <a href="http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080149a1f.shtml">http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a0080149a1f.shtml</a> and specifically reading "IP Phone user hears echo" paragraph, I can't say which direction(s) is (are) involved (as article don't mention which voice is echoed).<br>
<br><br>Another interesting thing to note in this paper is the "<span class="content">solution is to use a load ID on the IP phone, which includes echo
suppression on the handset and headset" (PSTN phone user hears echo).<br>Does it imply echo cancelling is mostly done inside phones ?<br>In an IP phone, is it more cost effective to use 2-wires connections (which produces echo) AND echo cancellation systems to suppress echo than to use 4-wires connections which don't produce echo in the first place ?<br>
Does it also imply that Cisco IP phones use 2-wires connections ?<br><br><br>Cheers<br> </span></div></div></div>