[Asterisk-Users] Reducing echo on FXS port

[Matt Riddell (IT)]

Aryanto Rachmad wrote:
> Hello everybody,
> 
> I am sorry to bring this up again if this kind of echo issue has ever discussed.
> 
> Phone2 in below call path experiences quite annoying echo:
> 
> Phone1 --> FXS (TDM400P) --> Asterisk --> SIP GW --> PSTN --> Phone2
> 
> It is annoying as on phone2, we can hear the whole words we say with the level of maybe 25% of the original sound. I can reduce the echo to maximum with the following settings for my FXS port on zapata.conf:
> 
> rxgain=-8.0
> txgain=2.0
> echocancel=256
> echotraining=500
> 
> But it is still not entirely eliminated as we still sometimes hear the last syllables, with the level of maybe 5% of the original sound.
> 
> What I did was just playing around with the values of those parameters, use ztmonitor to have the FXS rx/tx signal visualised and use only my ears to check it. I think my ears are fine :), as I do this because my friends complain about the echo they hear.
> 
> Does anybody know a better method to find the best value for those parameters?
> 
> There is no echo on phone2 when I use softphone like this:
> 
> PC(X-Lite) --> Asterisk --> SIP GW --> PSTN --> Phone2

Are you sure that X-Lite is not running an echo can?

I'd say it's more likely that the SIP GW is causing the echo and that 
when you use X-Lite, it's echo cans are removing the echo.

Try to make a call from Phone->FXS->Asterisk->X-Lite

I suspect there will be no echo.

BTW what is the SIP Gateway?

-- 
Cheers,

Matt Riddell
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