If I work in CCM 4.0, and I already merged my Network to 6.0. Do I have to make an upgrade to the Unity???
probably just verify the TSP version is compatible and doublecheck the config looks good on the CUCM side
SCCP Compatibility Matrix: Cisco Unity, the Cisco Unity-CM TSP, Cisco Unified CM, and Cisco Unified CM Express
if this helps, please rate
I think the only caveat is that Unity 5.x will not work with CUCM 4.0, 4.1 (but will work with CUCM 4.2)