I'm trying to simulate the situation:<div><br></div><div>SIP <----> Asterisk <-------> PSTN</div><div><br></div><div>In this case 16 ms works? </div><div><br></div><div>I've read in voip-info: <span class="Apple-style-span" style="font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); ">"</span><span class="Apple-style-span" style="font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); ">Simplistically, you'd need a "tail circuit" (the distance between your echo canceller and the source of the echo) of over 2500 miles to acheive an echo path of 30ms [...] </span><span class="Apple-style-span" style="font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; font-size: 12px; background-color: rgb(255, 255, 255); ">Asterisk's default of 128taps will therefore handle echo paths of up to 16ms, and is therefore probably good for most things.".</span></div>
<div><font class="Apple-style-span" face="Verdana, Geneva, Arial, Helvetica, sans-serif"><span class="Apple-style-span" style="font-size: 12px;"><br></span></font></div><div><br><div class="gmail_quote">2011/9/14 Kevin P. Fleming <span dir="ltr"><<a href="mailto:kpfleming@digium.com">kpfleming@digium.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="im">On 09/14/2011 10:14 AM, Eric Wieling wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
If I read Kevin's post correctly, his statement applies to ALL echo cancellers, not just software EC.<br>
</blockquote>
<br></div>
That's correct; regardless of whether the EC runs on a DSP or on the host CPU (or is a device in the path of an T1/E1 circuit), if it can only handle a 16ms window for echo cancellation, then having a packetized 'hop' in the audio path is likely to make it unable to do its job at all.<br>
<br>
Echo cancellers used on networks where packetized audio is transported through at least one hop need to be configured for (at least) 64ms windows, if not 128ms.<div><div></div><div class="h5"><br>
<br>
-- <br>
Kevin P. Fleming<br>
Digium, Inc. | Director of Software Technologies<br>
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</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br>Atenciosamente,<div>Gustavo Santos.</div><br>
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