Hi Alex,
When CUWL was purchased a messaging option would have been selected. Your supplier should be able to provide the Bill of Materials detailing this or you can just look at which disks you have in your CUWL folder.
If you have Unity Connection 7.1 that is great - you can install it and obtain the licenses you have obtained from the relevent PAK codes. With CUWL upgrades you are expected to use your existing Unity Mailbox licenses. You will need to get these rehosted if you have new servers as they are tied to MAC addresses (this re-use of licenses for CUWL upgrades is infuriating IMO).
If you have Unity disks then you can request a migration to Unity Connection using the PUT tool. The part code below will provide this.
MSG-UCXN-UWL-MIG | Messaging Migration to Unity Connection - CUWL only |
Hopefully this should get you started. You may need to order additional items for High Availability - the whole license setup is a bit of a minefield!