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Conference Problem

Seeing a problem where conferences, including internal only are exhibiting silence every 4-5 minutes with the silence lasting about 10-15 seconds, then the call resumes.  It appears the MRGL/MRG for the initiating phone is set up to pull CFB resources from the 3 CMs in the cluster first, so it doesn't appear to be a DSP issue.

Any ideas where the silence may be coming from?

4 Replies 4

Cisco Employee
Cisco Employee

Hello Cristopher,

Have you tried to use hardware based conference bridge?

Caution     Although a single software conference device can run on the same server as the Cisco Unified CallManager service, Cisco strongly recommends against this configuration. Running a conference device on the same server as the Cisco CallManager service may adversely affect performance on the Cisco Unified Communications Manager.

Please try to use hardware conference bridge and check id the problem persists.

You cóuld be facing some performance issues on cucm.

Thanks for the response.  Although best practices say to use hardware, I don't believe the setup I am seeing here is unusual, especailly is the total number of users isn't anywhere near the CUCM capacity (they have 1 pub and 2 subscribers and they are not heavily loaded). Additionally, this has apparently been working for at least a few years (I didn't set this site up).  There has been no recent growth or anything that I am aware of that could account for a load increase.  I conducted some tests yesterday but I did not encounter the problem.  I am going to be testing again during a high use time to see if the problem occurs.

At this point, since the issue occurs in a regular timed cycle, I suspect something in the network is fighting for access control - maybe something flapping.  Signalling does not appear to be affected, only the audio stream so it might also be something in QoS - it's not clear at this point.  I have also engaged Cisco TAC.

I will update here as things progress.  Thanks again for the response!

Nishant Savalia
Level 4
Level 4

Hi Christopher,

Silence issue is for all the customers for specific?

Where are the customers located..I mean locally or remotely connected to CUCM?

Please do share the detailed trace of call manager and IPVMS if possible?

Have you checked for any VAD setting?

Thank You


Regards, Nishant Savalia

Cesar Ortega
Level 1
Level 1

Have you enough DSP ressources for conference and transcoding (xcode) ?

Try on the gateway

sh voip rtp connections

See if calls uses the same codec when conference. If not, maybe a transcoding problem is the cause.

If it isn't the case, try changing the voice gateway IOS.



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