We have a serious voice quality issue with the Conference calls. The IPT Network includes 68 sites nation wide with a centralized topology. There's absolutely no quality issue between two IP Phones but as soon as we conference few people, the quality gets affected greatly. The CallManager is 4.0 and the most of the Gateways are 2620 with few 2650 and 2610. Please note that the voice quality for the initiator of Conference call is not as bad as the other participants. The average jitter gets up to 450 and that's when everybody breaks up. The RxLost is 0000 even during the bad quality. We have 10 CFB, 7 MRG and 13 MRGL configured in the CallManager. Could you please let me know how can I resolve this issue?
first comment, I would remove the attachment and re-add it without the passwords in it, and maybe even mask the ip addresses out. Security and all that.
Second, you have a pretty complete QoS architecture.
Since you labeled the serial interface as being an AT&T IPFR, I can comment that diffserv based Qos is honored on that network, but you do have to request it from AT&T. There is a posibility that AT&T is delaying your carefully tagged traffic.
Lastly, we have found that allowing bursting on frame circuits is a sure fire way to have poor quality. We spec the port and PVC to match eaxactly or as close to exactly as the carrier will allow.
Since you are not apparently using IOS conference resources, my comment about SCCP/TOS may not apply.
What are you using for conferencing, Call Manager resources, VG200 or catalyst DSP blades? Are your remote sites using G729? Is so, where are your transcoders?
Thanks for the advice. I removed the attached file. I will definitely verify with the telco.
I think we are using CallManager resources. I can see 48 availabe resources in Window Performance Monitor. How can I identify if we are using CallManager resources or DSP blades. We are using VG200 only for our Fax Machines
The remote sites are using G729 and we don't have any transcoder.
OK, what hardware provides that resource? I did not see a configuration in the sample router config you posted.
If it is on an IOS router, the issue may be QoS. The SCCP stack on the router that provides the CFB/MTP/Transcoder does not support DiffServ, so depending on your QoS strategy, those packets will not be matched/tagged. You can use a class map to match TOS 5 and retag it to diffserv EF, but that means that existing properly tagged packets will also be retagged.
I'de suggest a test plan to check three local phones using an Adhoc conference and a meetme, as the phone should be able to mix a three party call without a CFB resource. By keeping the phones local, you also avoid transcoding.
If that test produces good results, I would look closer at the CFB hardware settings (IOS or CatOS) and consider the QoS issues mentioned above.
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