We currently have an Exchange 2007/2010 environment in production along with Lync 2010 (UM provided).
I have installed a number of Exchange 2013 server and will be migrating ( over a LONG time ) to the new system.
In the meantime, I need to have all services co-existent across all three Exchange versions.

It looks like I have everything workign now except UM for Lync 2010.
I tried adding the Exchange 2013 server into the existing 2007/2010 dial plan and am having issues.

Here is what i did.

EAC
- Installed certificate on all Exchange 2013 servers
- Enabled Unified Messaging on all the servers
- Select server
- Set TLS
- Associated 2007/2010 Dial Plan
- Set UM service on certificate on all servers
- Restarted UM service
- Did the above for all MB and CAS servers
- Wait about an hour

Lync fails to send calls to voice mail, giving me events 45024 and 44022 on the Lync FE stating that Lync could not connect to the Exch MB servers and the attempt to connect to UM failed.
 
Any suggestions?

Do I need to rerun the following ?
- Exchucutl.ps1
- Ocsumutil.exe

Thanks!
Tom

You definitely need to run Exchucutl.ps1. This will create a new UM IP gateway in Exchange 2013 for Lync and associate all the existing dial plans to it.

Ocsumutil.exe is used to create contact objects so that Lync can route to Exchange. When you migrate your dial plans, auto attendants etc to Exchange 2013, you will use this tool to create associations to the new UM server.

I normally recreate the dial plans etc on the new UM server and create new contact objects. This way both old and new will carry on working and its just a matter of moving the number over.

Hope that somewhat answers your question.

When I go into the Exchange EAC Unified messaing / UM IP Gateway screen I see the Um IP Gateways configured in the legacy Exchange systems and had hoped that these existing gateway definitions would suffice.

Does exchucutil.ps1 need to run from a 2013 Exch server to initialize these gateways in Exch 2013?

On my fist attempt, VM was failing for my 2007/2010 users. I had not even started to test with a 2013 user. I successfully backed out by dis-associating the dial plan in the Exchange EAC console from all the Exch 2013 servers.

If I run exchucutil.ps1, try again, and it fails, what is my backout plan? Do I need to rerun exchucutil.ps1 on a legacy Exchange system? or will merely dis-associateing the diual plan in Exchange 2013 again suffice.

Thanks Tom

After typing this, I realize that this is probably more of an Exchange question so I posted the question there. I apologize now for any cross posting misbehavour.

Posted to - http://social.technet.microsoft.com/Forums/exchange/en-US/6fbfad13-3480-46c6-804d-3757110e61c7/exchange-um-coexistence-exch-20072010-and-exch-2013?forum=exchangesvrunifiedmessaging

Hi,

you need to run the .ps1 in all Exchange servers and get the UM IP gateway configures. Then try calling the VM from the clients.