[asterisk-users] echo cancellation for sip phones

[Pezhman Lali]

thanks for your writing
the network is like behind:

Sip phone(caller)--->SER---->Asterisk----> world telephone carrier--->pstn-->callee

the carriers and their routers are not accessible for us , the callees have not any echo in their  callings but the caller(sip phones) has the echo.
there isn't any telephone cards on our servers(SER and Asterisk) , all of calls are come from or going out , on internet connections


--- On Thu, 11/20/08, Alan Lord <alanslists at gmail.com> wrote:
From: Alan Lord <alanslists at gmail.com>
Subject: Re: [asterisk-users] echo cancellation for sip phones
To: asterisk-users at lists.digium.com
Date: Thursday, November 20, 2008, 12:01 PM

Pezhman Lali wrote:
> Dear,
> the sip phones that registered, in to the asterisk 1.4.x have the echo 
> in their callings to pstn.
> how this echo can be canceled?

Hmmmm - you don't give much to go on...

What is the connection to the PSTN (i.e. what kind of card, interface 
etc...)

The echo is almost certainly coming from that area rather than the SIP 
phones themselves.

If you have an analogue PSTN card without h/w echo cancellation, I would 
suggest trying the OSLEC echo canceller. This is[was?] not installed by 
default with the zaptel drivers.

HTH

Alan


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