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So you have 2 T1's terminated on the same IAD? Are they in the same
module or what? There are some interesting things that happen with
multiple clocked circuits terminated on these boxes. Can you clarify
which interfaces you are using for what on the IAD? Config snippets
always welcome.<br>
<br>
/Wes<br>
<br>
<br>
On Wednesday, May 06, 2009 5:00:03 PM, Jeff Anderson
<a class="moz-txt-link-rfc2396E" href="mailto:ciscoplumber@gmail.com"><ciscoplumber@gmail.com></a> wrote:<br>
<blockquote
cite="mid:112a29d30905061400y21ddb235m2d88c0453d69053b@mail.gmail.com"
type="cite">
<div>I have a couple of customers who are experiencing poor audio
using an IAD to connect their PBX to our h.323 PSTN GW.</div>
<div> </div>
<div>Basic Layout.</div>
<div> </div>
<div>Customer PBX PRI > IAD PRI (Network-emulate) converted to
VoIP > MPLS enabled T1 > Core > AS5850 (VoIP converted to
TDM) > PSTN.</div>
<div> </div>
<div>The customer reports that poor audio is experienced inbound into
their PBX. They say their outbound audio is okay. This doesnt happen on
every call but we do have more than one customer reporting the issue.</div>
<div> </div>
<div>The audio can be described anywhere from echo, cutting out or
distorted audio. The problem has also been reported by users who have
38xx series gateways so i dont think the problem is IAD specific. The
AS5850 is a shared device used by many different customers, the
majority of which connect using Cisco IP phones and this demographic of
customers are not reporting the problem.</div>
<div> </div>
<div>I have done packet captures on the AS5850 and there is no packet
loss reported, the packets arrive in sequence and the jitter is very
low.</div>
<div> </div>
<div>In my testing, I have found double-talk to cause the far end
audio (AS5850) to cut-out. All the packets arrive but they contain a
payload value of 7F. Some improvement can be made to this condition by
disabling non-linear progression. </div>
<div> </div>
<div> </div>
<div> </div>
<div>My questions for the community are related to experiences or
lessons learned from using PRI network emulate.</div>
<div> </div>
<div>Can there be too many echo cancellers in the call flow? (i.e.
Customer PBX UC500 with Cisco PRI, IAD PRI, AS5850 PRI all with echo
cancellers)</div>
<div> </div>
<div>Does the cable length command have any bearing on voice quality?</div>
<div> </div>
<div>Are there any special commands i should enter when connecting
back to back wth a T1 cable (echo-cancel coverage, nlp, etc)?</div>
<div> </div>
<div>Is a 2 pair sheilded T1 cable necessary for the PRI back to back
connection of less than 20 ft?</div>
<div> </div>
<div> </div>
<div>Any insight or suggestions would be greatly appreciated. </div>
<div> </div>
<div>Thanks,</div>
<div> </div>
<div>Jeff </div>
<div> </div>
<div> </div>
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</blockquote>
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