Two Unity and Call Manager Clusters Merge to One Exchange Box

Unanswered Question
Mar 11th, 2010

I was hoping someone would be able to verify if the following is possible.

Our organization is partialy absorbing a smaller organization.

We currently have a full VoIP setup with the following:

Call Manager:

Unity: 4.2 Build 4.2(1)

Rightfax: 9.4

Exchange 2003

The organization we are absorbing has the following:

Call Manager:

Unity: 4.2 Build 4.2(1)

Rightfax: 9.1

Exchange 2003 (going away)

Under the "merge" all of their users, computer and servers will be brought into our Active Directory structure. Their exchange users will be brought into our exchange enviroment. Their phone numbers are in a different area code, the last four digits have no overlap with ours (thankfully).

On the table there are 3 different proposals, the last of which is outside of the scope of this question. I believe that either of the following two options should work based on the documentation I've looked over but would love to hear a confirmation from someone that it is indeed the case.

Option 1 (The prefered method)

Their entire phone infastructure stays in place. Users are placed into our exchange enviroment. Their Unity would point to our exchange, This would effectively have two different Unity systems (ours and theirs) pointing to the same Exchange box. The same situation would occur for their Rightfax box.

So alll in all 2 Unity and 2 Rightfax servers pointing to 1 exchange box. The callmanagers would be left out of the equation. Their users would remain seperate from ours for all phone purposes aside from exchange voicemail and fax account locations. From my understanding of the documentation, this would effectively create two seperate voicemmail stores on the exchange server

I guess aside from confirming that exchange can support two different unity boxes, the other issue I'm running into is finding the location where you change the exchange partner server unity is looking for.

Option 2 (Secondary Proposal)

Their Call Manager Stays in place. Users are placed into our exchange enviroment. Their RFax and Unity boxes are removed. All users faxes and voicemail are run off our RFax and Unity boxes.

This I'm almost 99% positive should be an issue but would require a bit more backend work, a second cluster integration on our Unity and RFax as well as an extensive reconfigure of their voicemail settings in call manager.

I really appreciate any confirmations from people who have gone through similar mergers, particularly for the Unity part.



I have this problem too.
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Tommer Catlin Tue, 03/16/2010 - 09:13

So here is my take on this.

Exchange can support (2) different Unity servers.  As long as they are in the same Forest.  If they are in a different AD Forest, it will not work.

If you are going to break down their exsiting AD domain and merge it with your domain:

One Forest, One Exchange

(2) Unity servers.

(2) CUCM clusters

The CUCM clusters can be ICT (Inter Cluster Trunk ) setup to call between the clusters.  No issues there.

CUCM can also have (2) LDAP directories added to it.  So the IP phones can have the same directory throughout.

Each CUCM can have its own Unity server.

Long term, here is what I do.

If this "One" company is perm, plan on a single cluster design.

Purchase new hardware for CUCM to support CUCM 7x./8x

Install as CUCM 5.x

DRS Backup old cluster (just one)

DRS Restore to new 5.x cluster on new hardware

work on BATing out phones from the other 5.x cluster and BATing back into the new 5.x cluster hardware

Move Unity server over if needed, or install new Unity server 7x or Connection 7.x/8.x and migrate to one platform.

Once everyone is on the same cluster 5.x, new hardware.  Run a CUCM 7.x inplace upgrade.

In the end, you will have less hardware/software to support from CallManger/Unity.  If there is no business need to have to separate clusters, it will be cheaper in the long run to break down the dual enviroment and have single CUCM / Unity cluster to support.

Now, if there are geographical limitations (global), then it would make sense to have multi-cluster.  But if its only US only, you should move to a single cluster design.

Hope this helps


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