I upgraded a Cisco Unity unified messaging server from version 4.2 straight up to version 7 the other night. The whole process took a little less than 5 hours from the time we started until the time we finished testing everything. I expected it to take less time but the existing Windows 2003 Server operating system was not running SP2. Applying SP2 via the CUSPA tool took over an hour. I couldn’t find specific 4.2 to 7 upgrade documentation so I followed the 4.2 to 5 guide on cisco.com. If you upgrade from 4.x to anything 5.x or newer you must rerun the schema extensions. We ran the schema extensions earlier in the day to be sure that it had time to replicate. All in all everything went off without a hitch, no problems, it simply took time.
-Go0se