[asterisk-users] screeching noise on zap channels

[Col Ferguson]

----- Original Message -----
From: "Steve Totaro" <stotaro at totarotechnologies.com>
To: "Asterisk Users Mailing List - Non-Commercial Discussion"
<asterisk-users at lists.digium.com>
Sent: Monday, April 07, 2008 10:28 PM
Subject: Re: [asterisk-users] screeching noise on zap channels


> On Mon, Apr 7, 2008 at 8:17 AM, Col Ferguson <asterisk at coltect.no-ip.com>
wrote:
> > I have been working on a system where sometimes the users get a horrible
> >  screeching noise that gets louder, typically as a call is hung up.
> >
> >  The system has 2 analog astribank channels with 8 FXO and 56 FXS ports,
and
> >  2 SIP phones, Asterisk 1.4.18, Zaptel 1.4.9.2. It is using the oslec
echo
> >  canceller.
> >
> >  In my testing, I have only experienced it on hang up of a call, but
some of
> >  the users say they have heard it at other times. It sounds like
feedback
> >  building up. The Receptionist said she had taken about 40 calls this
> >  morning, and had only heard it once.
> >
> >  Because of the nature of the noise I have heard, I suspect something
with
> >  the echo cancelling, but I have no idea where to start looking. Maybe
it
> >  would just be easier/quicker to try a different echo canceller.
> >
> >  There is no noticable echo during conversations.
> >
> >  No one has heard the noise between the 2 sip phones, but as it seems
> >  intermittent, this may be irrelevant.
> >
> >  Any hints as to how to track this noise down ?
> >
> >  Thanks,
> >  Col
> >
>
> Start by turning off echo can on your zap channels.  I have setup many
> analog FXI systems that never needed echo can.
>
> Thanks,
> Steve Totaro
>

Thanks Steve,
I suppose that would be a good place to start testing.

Col


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