I'm planning to upgrade our CUCM cluster to 7.1.2.(1Pub + 1 Sub). Current version is: 18.104.22.1680.11. Is there a way to upgrade directly to 7.1.2, o r I have to upgrade to 6.1.2 and then to 7.1.2 ? What server should upgrade firstly? Can I upgrade one of them and the other after a week? Any help will be wellcomed.