Our company is currently running CM 4.1 on Windows 2000. We are looking at upgrading to Server 2003 with CM 4.3. Before making this move, I was curious if there was any real advantage to upgrading to UCM 6.1 with the Linux operating system? Is there any major feature differences between 4.3 & 6.1? Or is the operating system the only real major change?
4.3 has most of the features you would want these days.
6.1 has the new mobility manager / single number reach which is interesting.
The appliance OS is much nicer to manage. Easier to backup, no windows problems. Much simpler. Fewer patches, much easier upgrades to CallManager, and easier rollbacks.
If your interested in v6.1 you can run it up in a lab environment on VMWare to have a look.