[asterisk-users] RE: ECHO Cancellation in SIP Calls

[Jerry Jones]

You will also perceive jitter as echo

If any links are getting busy and routers or switches have to buffer  
you will hear what sounds like echo, not to mention if you have a  
high packet loss also

Of course jitter would have to be above 100ms or so to be noticeable

as far as acoustic echo, i have had to put 192ms tail ec on pri  
direct from carrier because of so many networks interconnecting and  
doing poor jobs and that 192ms is not going to be enough shortly

yes traditionally telco echo originated at 2wire to 4 wire transition  
points or on hybrids hence it is usually referred to as hybrid echo  
versus acoustic echo which does happen in an all digital call. This  
is one thing the better quality phones give you some control of.

I am starting to look at dedicated aec hardware to handle even all IP  
calls


On Oct 26, 2006, at 9:56 PM, Michael Araba wrote:

> I am surprised that you are getting echo on SIP calls. You can get  
> echo
> in two scenarios on SIP calls.
>
> 1. If SIP calls are crossing to PSTN (inbound/outbound). Here you need
> to enable echo canceller and AGGRESSIVE if needed in zconfig.h.
>
> 2. Second source of echo on SIP calls could be ACOUSTIC. The phone  
> sets
> you are using may not handle this well.
>
> In my experience sound quality deteriorates if there is network  
> trouble
> or congestion on SIP calls
>
> I hope this helps.
>
> Michael
>
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