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New Member

CUC integration issue


I am strugling to get the MWI indicator to work across SIP for a new cluster. The setup is as follows:

Additionally, this is how the IPTel servers are configured:

CUC Cluster (2 servers)--->SIP Trunk ------>to Older CUCM Cluster (2 Servers); MWI works fine for these users---->SIP Trunk(NOT ICT) ----->to New CUCM Cluster (2 servers) . Both old and new CUCM Clusters are in use  and serve different set of users. Both the CUCM clusters have same number as Voicemail Pilot.

The phones are combination of SIP and SCCP (both having issue) but they never receive the SIP message to turn on the MWI. Moreover, the CUCM cluster in the Middle seems to send out 4XX SIP error message (client error) as if it is trying to send out the message but can not  figureout where to send it.

I strongly suspect that its integration issue so I need to know if this setup is known to work.

Thanks in advance.

Everyone's tags (4)
New Member

CUC integration issue

Forgot to mention, on CUC there is only 1 Phone system configured. But I am not sure if this is going to cuase an issue as both CUCM clusters belong to same company.

Hall of Fame Super Red

CUC integration issue

Hi Gaurav,

I'm pretty sure that to support MWI in this configuration you would need


1. A QSIG ICT between clusters


2. A separate phone system integration for each cluster.



"Every fool's got a reason to feelin' sorry for himself" - Springsteen

New Member

CUC integration issue

Thank you Rob for replying to my Query. It took me some time as I was testing the setup in lab and it seems to work on CUCM 8.6(2a)SU2 which is recently released and on the version that our client is using 8.6(2a)SU1.

I was also able to isolate the issue by using packet capture on Intermedialte CUCM.

The problem seems to be with digit manipulation on GW (this is why the problem did not replicate in lab and CUCM DNA was not able to point it out). Also, MWI across the SIP Trunk from 1 CUCM cluster to another works fine which also suggests something wrong with external calls.

CLID for all the calls is being transformed into a single number for this site and even though the Call reaches individual voicemail box on Unity based on ANI, the MWI gets screwed up. I will be doing more troubleshooting around GW tomorrow and post my findings.

Do you know what role would the ANI have in CUC SIP messages?

Thanks in advance.

New Member

CUC integration issue

Just an update:

The MWI feature is suppose to work on SIP trunks, irrespective of QSIG (

It started to work in my situation after service restart.

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