There is a little more than that, but it's a good start.
Your service provider should already have told you about a bunch of settings it requires: protocol, sequence and framing, for instance. You will need to put the correct values under Hardware > Cards on KSU > [Cartridge].
Also, on a PRI, outgoing calls are made using the Routing Service. If you are already using the Routing Service to make outgoing calls, you will most likely need to change the line pool to PRI-A. If you are not using the Routing Service at all, you will need to set one up.
And before going any further, you should definitely check the software version you are running. There are known issues for PRI with MICS 6.1. These issues were solved in MICS 6.1 MR. So, if you are currently running MICS 6.1 (not MR), you should plan an upgrade to a later release first.