Problems with conference bridge on CUCM 5.1.3

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Sep 23rd, 2010
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Hello all

I am having trouble with conferencing on one of our remote CUCM cluster. At present we are only getting two party conferencing. The CUCM has been configured with a SW conference bridge on both the pub and sub.

Any sugestions??



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Lakshmi Adapala Thu, 09/23/2010 - 03:56
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Check to see what codec (region relationships) is being used between the phones as CUCM software conference bridge can only support G.711 codec. Also check the region relationships between the conference bridge and each of the phones as if this is not G.11 then conference bridge will require access to a transcoder so that transcoder to cof is G.711 and transcoder to the phone will be G.729

simonmossman Thu, 09/23/2010 - 04:09
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Thanks for the reply

I have an ios transcoder configured as below

sccp ccm group 1
associate ccm 1 priority 2
associate ccm 2 priority 1
associate profile 2 register MTPAUKOCRO001
associate profile 1 register XCDAUKOCRO001
dspfarm profile 1 transcode
codec g711ulaw
codec g711alaw
codec g729ar8
codec g729abr8
codec gsmfr
maximum sessions 2
associate application SCCP
dspfarm profile 2 mtp
codec g711ulaw
maximum sessions software 30
associate application SCCP

Jaime Valencia Thu, 09/23/2010 - 04:26
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And does it show as registered in CUCM and is the phone that is trying to create the conference able to reach it via it's MRGL??

It needs to be in a MRG that is before the one that has the SW CFB if you expect non-G711 callers (or at least make sure this CFB can access the XCODER)



If this helps, please rate

simonmossman Thu, 09/23/2010 - 07:53
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Hi Java

All is registered and ok.....but Well mentioned......the MRG does not have the xcode media resource included


Felipe Garrido Thu, 09/23/2010 - 06:38
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Did you verify that the IP phones have access to the conference resource via their MRG/MRGL configuration? If it is a codec mismatch issue, the transcoder is only configured to support 2 sessions which won't be enough to sustain a conference call.


simonmossman Thu, 09/23/2010 - 07:58
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Hi Felipe

Well mentioned also......the xcode will only support 2 sessions and all calls are G729 accross the WAN. Aas mentioned to Java.....the MRG did not have the xcode resource available anyway....this can be rectified by simply adding it...


What would you do in this scenario?

Up the max xcode sessions or create a HW conf bridge on the GW?


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