Hi TT,
I hope you are doing great. Let me start by saying this:
"Everyone has these kind of questions in some phase of their careers. So it is not an immature question."
1)Please check this thread:
https://supportforums.cisco.com/thread/2037416
*Unrestricted version is customised for some special countries. Most of the other countries including US use restricted version. (Signaling and Media Encryption is permanently disabled in Unrestricted version but not in Restricted Version)
*You can always upgrade from Restricted to Unrestricted version but not vice versa.
2)Upgrading to version 8.6 involves an altogether different method of Upgrade Called "Refresh Upgrade" and thus needs to be very well planned. Please have a read of the following blog written by me:
https://supportforums.cisco.com/community/netpro/collaboration-voice-video/unified-comm-application/blog/2011/08/11/checklist-before-upgrading-to-unity-connection-86
Though the above blog is for Unity Connection, the upgrade process pretty much remains the same for the fact that both CUCM and Unity Connection run on UCOS platform.
3) Since you are moving from one major version to another major verison (ie. 7.x to 8.x) , you need to have upgrade license.
Please contact licensing@cisco.com with mac addresses of the servers and PAK.
For hardware requirements, read the following manual very carefully:
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/rel_notes/8_6_2/cucm-rel_notes-862.html#wp2041345
I hope this information will help you plan the upgrade better.
Regards,
Saurabh Agnihotri
