About a month or so ago, I was asked by a colleague if there were any issues with upgrading Exchange Server 2010’s Unified Message server from RTM to SP1 if Cisco Unified Communications Manager (CUCM) was using it for voicemail. Though I wasn’t able to give him an answer and he ended up having to look for the information himself, I’d like to share his findings.
What my colleague basically dug up through research was that while he wasn’t able to find anything concrete with respect to challenges faced or concerns when upgrading from Exchange Server 2010 RTM to 2010 SP1, he did find a few blog posts that indicated problems with CUCM 7.x. The following is a link to a forum post with people experiencing problems after the upgrade where Exchange would reject the incoming call with the message:
"Invalid Route header: mismatched character: expected: '"', found: 'EOF'"
This appears to affect only version 7.x and not 8.x.
So please be careful when upgrading to SP1 if you’re planning to do so.