The way I see it, you would need to schedule an outage window, just to be safe. Then, remove the ports from the Unity Connections system. You will probably need to remove the last 50. since I don't know how you have a HA pair of connections servers, you may need to change some of the ports around as to what server they are on and what there purpose is (answer, mwi, dial out, etc). Then you will need to do the same thing on the CUCM side, remove the last 50 ports. Again, not knowing your setup, you may need to adjust your line groups.
Example of what I am saying
Unity Server 2 100 ports 90 answer 10 mwi
Unity Server 1 100 ports 90 answer 10 mwi
You would delete the last 50 ports, which would be the 10 mwi ports and 40 answer ports on the publisher server. You would then need to reconfigure to 75 ports per server with how ever mwi ports are needed.
Unity Server 2 75 ports 65 answer 10 mwi
Unity Server 1 75 ports 65 answer 10 mwi
In doing so you would need to change the last 25 ports of Unity Server 2 to Unity Server 1 and then adjust the capabilities of those ports so that they line up.
Then on the CUCM side, you would need to delete the last 50 ports and adjust your line groups so they match the new port configurations.
After everything is complete, you would probably want to do a reset on the Hunt Pilot, Hunt Lists, Voicemail Ports in CUCM and then also reset the Port Group in CUC. After completion, you should verify all ports are registered and then test to ensure functionality.
I may have missed something, but that is the steps I would take. I would run through it in a lab first if possible just to make sure you got the process down with no gotchas
Thanks
Nathan
