[asterisk-users] Echo issue

[hin lee]

The echo between our extensions (using Polycom 550 handsets)  disappears once I removed the Digium echo module.   We are still experiencing some echo on land line calls, using dahdi to connect to our PRI circuit. 

What kind of settings do you recommend for the "txgain and rxgain"?  Do I make the gain changes in chan_dahdi.conf?

Thank you!

This is my system.conf:
===================================================
# Span 1: WCT1/0 "Wildcard TE121 Card 0" (MASTER) 
span=1,1,0,esf,b8zs
# termtype: te
bchan=1-23
dchan=24
echocanceller=mg2,1-23

# Span 2: WCTDM/0 "Wildcard AEX410 Board 1" 
fxoks=25
echocanceller=mg2,25
fxoks=26
echocanceller=mg2,26
fxoks=27
echocanceller=mg2,27
# channel 28, WCTDM/0/3, no module.

# Global data

loadzone    = us
defaultzone    = us



This is my chan_dahdi.conf
============================================================
[trunkgroups]

[channels]
context=from-pstn
signalling=fxs_ks
rxwink=300              ; Atlas seems to use long (250ms) winks
usecallerid=yes
hidecallerid=no
callwaiting=yes
usecallingpres=yes
callwaitingcallerid=yes
threewaycalling=yes
transfer=yes
canpark=yes
cancallforward=yes
callreturn=yes
echocancel=yes
echocancelwhenbridged=no
faxdetect=incoming
echotraining=800
rxgain=0.0
txgain=0.0
callgroup=1
pickupgroup=1

;Uncomment these lines if you have problems with the disconection of your analog lines
;busydetect=yes
;busycount=3


immediate=no

#include dahdi-channels.conf
#include chan_dahdi_additional.conf


________________________________
From: Noah Miller <noahisaacmiller at gmail.com>
To: Asterisk Users Mailing List - Non-Commercial Discussion <asterisk-users at lists.digium.com>
Sent: Tue, December 8, 2009 7:37:28 AM
Subject: Re: [asterisk-users] Echo issue

Hi -

> I am having echo issues on our Asterisk box using a PRI circuit.  I was
> using the software echo cancellation and that helped a bit but didn't solve
> it completely.  So I went and bought a Digium echo cancellation module for
> the TE121 card.  That made it even worst, getting more echo on external
> calls and between internal extension to extension.  The echo doesn't happen
> all the time, but enough to get complaints from our users.
>
> Completely fed up with the issue, I removed the module from the card.  Can
> someone guide me on how to fix/tune/address the echo issues.

You can likely eliminate most echo on a PRI by setting txgain and rxgain.

Are you using dahdi or zaptel?  If Dahdi, what do your system.conf and
chan_dahdi.conf look like?  If zaptel, what do your zaptel.conf and
zapata.conf look like?

When you say you have echo on calls that are internal extension to
internal extension, are the endpoints using dahdi/zaptel or some voip
technology (sip, iax, mgcp, skinny, etc)?  If voip, any echo is
acoustically generated by the endpoints themselves.  On voip calls
I've often had this happen when the endpoints are using headsets, or
have gain levels set very high.


- Noah

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