[asterisk-users] HPEC > VPM ?

[Noah Miller]

>> Next question: does anybody know how to handle extremely long tail
>> echo that a VPM module cannot?
>
> How long is 'long' in this case? The VPMs and HPEC (and OSLEC) can
> handle 128ms echo tails, which is pretty darn long. It's rare to see an
> echo tail longer than that except on very high latency connections, or
> when the echo is actually acoustically generated by the far end and not
> by network effects.

I haven't done any real measurement on it, but I believe it's actually
longer than 128ms.  As I go higher and higher with echocancel values,
the echo does get better, but is never totally eliminated.  At
echocancel=1024, there is still rather pronounced echo on calls in the
"local" exchanges.  The calls are also more or less half-duplex at
that point because the vpm is filtering out so much of the signal as
echo.

I may just tell the client to look at a partial PRI.  All this echo
chasing is getting costly for them.


Thanks!
Noah