Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

One Exchange Server UM service for different UCM clusters?

Hi All,

I'm facing a challenge that when we have one Exchange Server UM with different UCM clusters. 

We have 1000 user configured UM with one UCM cluster and we're going to move 600 users to another UCM cluster. What I found is that, each user has been associated with the UM mailbox policy, and UM mailbox policy associated with Dial Plan, and Dial Plan is using the servers in the existing UCM cluster.

If I add the new UCM cluster to associate with the existing Dial Plan, where 2 UCM clusters are associated with the same UM Dial Plan in Exchange, the MWI won't work normally because it seems Exchange will randomly send the MWI indicator message to the UCM servers associated with the Dial Plan.

If I add another UM Dial Plan for the new UCM, then a new UM mailbox policy must be configured to associated with the new Dial Plan, and the users then need to be associated with the new UM mailbox policy, Which will bring a lot of user UM configuration changes in Exchange. We don't want to move the 600 users in a day.


Please kindly advise if there is any best practice in this situation which can minimize the change but the UM users can move to the new UCM cluster.


Thanks and regards,


New Member

Any suggestion will be

Any suggestion will be appreciated.