It seems that when planning a Cisco Unified Communications Manager (CUCM) upgrade, the amount of releases are sometimes dizzying! Can I direct upgrade or not? Do I need to PUT (product upgrade tool) for a license and CD? How do I match the release ID with the CUCM version ID (7.1(3a) vs. 126.96.36.19900-2). I know that pain and Cisco has created a tool to help us with the process. Check out the link here.
With this tool, you can input your version (supports only 5.1(3)+) and which version you want to migrate to. It will let you know if you can upgrade directly and what the licensing implications are. As a customer looking at upgrading to 8.x, this tool is a terrific resource for upgrade planning. Check it out!