No, the whole process really is what I've written above. The license file is purchasesd from Cisco, but once you have that file there is no further involvement with Cisco, it's all done on the CUCM.
You license the CUCM to accept a certain number of devices, and then as you add phones to the CUCM the license totals will go down.
The licenses are in units. So say you apply a license file that contains 1000 units. If you look in the License Calculator, it will tell you how many units each type of phone would use up.
Every time you add a phone (or sometimes a feature such as Mobility) it will use up a certain number of units as shown in the Calculator, and if you ever remove that phone later (say because it needs replaced because of a fault or for a newer model), the units are returned. So for example, a Cisco 7945 IP phone takes up 4 units each, whereas a 7975 uses up 5 units each.
Once you run out of units it won't let you add any more phones until you either remove some devices to get the units back, or you apply more units.
