Unity Connections upgrade question

[jkohlhoff]

hi all, I have in my environment a CUCM 9.1.2 system, Unity Connections 9.1.2 system, and a CER 9.x system.  I do not have PLM in my environment as of right now.  We are currently looking to upgrade our Exchange environment to Exchange 2016 thus needing to upgrade our Unity Connections system.  My question is, can I just upgrade my Unity to 11.5 or do I have to upgrade everything to the latest and put everything in PLM?  I have done all of my own upgrades in the past and they have always been straight forward but this one is something different.  Any help anybody could provide would be greatly appreciated! 

[Jaime Valencia]

CUC is a wildcard when it comes to upgrades, it's pretty much compatible with any CUCM version above 7.x, and that means you can upgrade it at any point in time.

Do make sure to read the upgrade guide and release notes before the upgrade.

[jkohlhoff]

I have been reading the upgrade guide and the release notes, I just couldn't find any information regarding if I had to upgrade CUCM at the same time I did Unity connections.  I was told once I go to PLM I had to upgrade everything in the environment to use PLM, which I found odd.  Everything I read said that CUC could work with CUCM 9.1.2 and mentioned nothing in regards to upgrading everything at once.  Thank you for the answer!