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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>It might be a transcoding issue. I
encountered something very similar with Cisco Conference Connection (CCC) and a
3640 using an HM-DHV farm module for transcoding. It turned out the CCC wasn’t
sending uniform G711 packet sizes to the 3640 for transcoding. We spotted this
with a packet trace. The packets kept varying in size from 20 ms to 10 ms and
back again coming from the CCC server to the router. The DSPs on the on the
router didn’t know what to do with the 10ms packet samples it just
dropped them. It made the speech sound very muddy. There wasn’t a
fix for the CCC software; Cisco is very slow on updating it. But we were able
to upgrade the code on the router later and it seemed to help. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>In your case the PVDMs are a little
different on the 1760V platform from the PVDMs in the NM-HDV modules in the
26XX/36XX/37XX router platforms. Also it’s the software conference bridge
on CM not CCC so it might not be the same issue.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>--Scott <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
cisco-voip-bounces@puck.nether.net [mailto:cisco-voip-bounces@puck.nether.net] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Kris Seraphine<br>
<b><span style='font-weight:bold'>Sent:</span></b> Thursday, February 17, 2005
7:48 AM<br>
<b><span style='font-weight:bold'>To:</span></b> cisco-voip@puck.nether.net<br>
<b><span style='font-weight:bold'>Subject:</span></b> [cisco-voip] multi-site
conference call voice quality degrades overtime</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hi<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I have a customer with a small two site cluster. When
they hold conference calls, everything works fine for the first 15 – 20
minutes but then the participant in the remote site will complain that the
audio becomes choppy or sounds like they’re “under water”.
These are meet-me conferences initiated by a user at the central
site (where the callmanagers are) using the callmanager software conference
bridge. The remote user calls across the WAN (g729) and uses a dsp
resources in a 1760 for transcoding. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>After 15 minutes or so the call quality will degrade for the
remote participant but other participants are able to hear the remote user and
each other fine. If the remote user hangs up and calls back into the
conference, it will sound fine but degrade again after 15 + minutes.
During one conference a user called in to the conference 4 times and the call
always degraded after 15 minutes. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I don’t think the WAN is an issue. They have
MPLS with guaranteed realtime bandwidth for 3 concurrent calls.
Callmanager locations enforce this limit and we’ve never had any call
quality complaints except for these conferences. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I have a case open with TAC but we’re not getting very
far with them. I’m wondering if anyone else has experienced a
similar issue. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><st1:PersonName
w:st="on"><font size=2 face=Arial><span style='font-size:10.0pt;font-family:
Arial'>Kris Seraphine</span></font></st1:PersonName><br>
<font size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'>Senior
Technology Specialist</span></font><o:p></o:p></p>
<p class=MsoNormal style='mso-margin-top-alt:auto;mso-margin-bottom-alt:auto'><st1:place
w:st="on"><st1:City w:st="on"><font size=2 face=Arial><span style='font-size:
10.0pt;font-family:Arial'>Clifton</span></font></st1:City></st1:place><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> Gunderson
Technology Solutions<br>
<st1:Street w:st="on"><st1:address w:st="on">1111 Deming Way suite 101</st1:address></st1:Street><br>
<st1:place w:st="on"><st1:City w:st="on">Madison</st1:City>, <st1:State w:st="on">WI</st1:State>
<st1:PostalCode w:st="on">53717</st1:PostalCode></st1:place><br>
Phone: 608.833.8638<br>
Fax: 608.833.0194<br>
Direct: 608.662.7640<br>
Web: <a href="http://www.cliftoncpa.com/" title="http://www.cliftoncpa.com/">www.cliftoncpa.com</a></span></font><o:p></o:p></p>
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