[cisco-voip] Cucm 8.0 to 9.1 upgrade

[GR]

Hi Guys,

Quick one - upgrading from cucm 8.0 to 9.1, with an active UCSS how much will it cost from licensing point of view - software feature license etc..?

Since this is a refresh upgrade need to install COP file as well. Is it any different in terms of outage? Can we reboot one server at a time like normal upgrades or whole cluster will be offline at any point  with this COP file while going from Linux4 to 5?

Thank You.
GR