[Asterisk-Users] Echo Cancellation Feature

[Tom]

At 02:30 PM 4/22/2004, you wrote:
>I would also offer feedback that we too have random calls with echo on our 
>end, that can't be traced to a reproducible event. It's very odd and can 
>be frustrating, as it's a big distraction for those that don't know 
>better. Like a bad cell phone connection when you hear yourself talk. For 
>us, this happens in a pure SIP environment on a network switch dedicated 
>to Asterisk, a T1 PRI and 18 SIP handsets.
>
>HTH,
>Ryan

We have three Cisco 7940 SIP phones and 1 POTS phone connected to our * 
server with  TDM10B fxs card.  Our * server is connected to the pstn with 3 
X100P cards.  We have similar echo problems but only on our SIP phones.  We 
do not have any echo problems with the POTS phone.

We just purchased a Polycom IP 500 SIP phone to test but I expect similar 
echo problems.

The recent thread which addressed milliwatt generators and gain adjustments 
helped to reduce our echo but the thread was never completed.  We are not 
sure how to test the TX gain adjustment and where on the graph to set the 
RX gain when using a milliwatt generator tone.

Tom

Tom


>On Apr 22, 2004, at 1:37 PM, Brent Franks wrote:
>
>>I do feel the echo cancellation does need some work.
>>
>>Currently, other than listening to users, there is no way to benchmark or
>>trouble shoot echo problems.
>>
>>We find that 2 to 3 out of every 20 calls will experience echo.  While
>>echo is a problem that naturally occurs from SIP - PSTN and vice versa, I
>>am still baffled by the fact that the cancellation works randomly.
>>
>><snip>