<html>
<head>
<meta content="text/html; charset=ISO-8859-1"
http-equiv="Content-Type">
</head>
<body bgcolor="#FFFFFF" text="#000000">
<br>
<div class="moz-cite-prefix">On 9/12/2012 5:33 PM, Sebastian Arcus
wrote:<br>
</div>
<blockquote cite="mid:50510DAC.8060406@open-t.co.uk" type="cite">On
10/08/12 18:38, Chad Wallace wrote:
<br>
<blockquote type="cite">On Tue, 31 Jul 2012 09:44:26 +0100
<br>
Sebastian Arcus<a class="moz-txt-link-rfc2396E" href="mailto:shop@open-t.co.uk"><shop@open-t.co.uk></a> wrote:
<br>
<br>
<blockquote type="cite">I have two setups with SIP hardware
phones as extensions and POTS
<br>
lines as trunks. Internal SIP to SIP calls are crystal clear,
but all
<br>
calls bridged to POTS have a significant amount of static
noise. The
<br>
problem is that if I plug a POTS phone directly into the line,
there
<br>
is almost no static noise - the line is clean. It's like
Asterisk (or
<br>
the hardware) amplifies the static noise. What I've tried so
far:
<br>
<br>
1. Connect Asterisk with a short cable directly into the
master phone
<br>
socket, where it enters the building.
<br>
2. One of the lines carries ADSL - so I double filtered it.
<br>
3. Tried three different phone sets (one Grandstream, two
Cisco
<br>
models).
<br>
4. Tried an OpenVox A400P PCI card and a Sangoma U100 USB
<br>
adapter as analogue-to-digital interfaces.
<br>
</blockquote>
<br>
Have you run fxotune? I remember doing that when we had analog
<br>
lines. You'd have to look up how--maybe just in the fxotune man
page.
<br>
<br>
<br>
</blockquote>
Thanks for replying Chad - and sorry for the delay in my reply. I
should have mentioned that I ran fxotune and made no difference. I
also checked the interrupts, and even changed motherboard, and
tried a USB analog adapter (Sangoma U100) instead of the current
OpenVox PCI adapter. None solved the problem.
<br>
<br>
I have given in and asked the client to order ISDN lines I'm
afraid.
<br>
<br>
Sebastian
<br>
<br>
<br>
</blockquote>
<br>
Sebastian,<br>
<br>
I understand it is too late for your client, but for the sake of
consistency.<br>
<br>
I am experiencing a similar issue with Digium TDM410 on FXS lines.
In my case the static noise is always present on analog extensions
provided by TDM410.<br>
<br>
I had a ticket opened with Digium, and they admitted the following,
but refused to make the findings public:<br>
<ol>
<li>The static noise is produced by Digium analog equipment on
certain motherboards. I specifically tried various Dell
Dimension Pentium III machines with several power supplies.
They all consistently started producing the noise the moment
DAHDI drivers loaded, even before Asterisk was loaded. When I
tried Dell Dimension Pentium IV machine the noise was not there.</li>
<li>On a machine which produced noise as described in #1 switching
to a non-Digium TDM card fixed the noise problem. FXS daughter
card stayed the same, just the base card was swapped.</li>
</ol>
<p>I do understand your situation involved FXO, and switching to
OpenVox or Sangoma did not help. But I feel the root cause well
may be the same.<br>
</p>
<p>Regards,<br>
Vladimir<br>
</p>
<p><br>
</p>
</body>
</html>