[Asterisk-Users] Re: Can anyone explain reason for this echo

[Andrew Kohlsmith]

On Friday 18 November 2005 00:30, Eric Bishop wrote:
> I purchased the following item:
> http://www.oriontelecom.com/echo_canceller/1u_telnet/e1_1u_19inch_ec.html
>
> As you can see not a very highly spec'd product but does the job well.

Perhaps not highly specc'd but with tail lengths of 64ms bidirectional or 
128ms unidirectional, it's already more capable than the software cancellers 
(16ms unidirectional with echocancel=128) and I believe that the VPM isn't 
all that much better, but I'm not 100% sure now that I can't find the specs 
on it.

> I don't accept the fact that mine is a special case. In fact if anything it
> should be better than most other scenarios as we are using Tier 1 hardware
> (all HP), Digium Rev 2 firmware and our rack is about 10 metres from the
> CO.

None of that really matters -- it's the overall disance from your RJ48 to the 
far end's phone that determines the TDM delay, and delays in your 
motherboard's PCI implementation that cause echo.   By far mostly the latter.

-A.