Exchange 2007 SP1 and OCS UM notes and gotchas !

So you've download Exchange 2007 SP1 and want to install it on your UM server that is integrated with OCS!?

If this is your first OCS integration then you should start is by downloading the documentation and if you've earlier downloaded the Office Communications Server and Client Documentation Rollup then you should go to the Office Communications Server 2007 Technical Library and find the documents updated to version 1.1 (Quite a few of the planning and deployment guides are updated to version 1.1 - not the Enterprise Voice Planning and deployment guide though)

Then the next place you should start reading is the SP1 Release Notes and especially the part covering Unified Messaging and "Issues related to the Unified Messaging server role"

In short the important general issues are -

• The Unified Messaging Server role must be installed on a dedicated role (Like in the Beta's)
• Configuration data is overwritten during installation !
• You must remove any language packs installed before installation of SP1

And most importantly when integrating with OCS the following issue apply -

• The Exchange UM server itself cannot request the MRAS credentials required to initiate an outbound call to a remote user (A user on the Internet External to the Edge), so for Play on Phone to work in this scenario the UM Server role needs to have cached credentials from a previous incoming call and reuse these !! (Read the full evasive explanation in the Release Notes)

There are a few other smaller issues applying to OCS/UM but the above is by far the most important one (And I guess hours could be spent troubleshooting if you are not aware of this issue)