Well, maybe you will or will not need a csu.
I've in stalled several where the T1 is "CREATED" right next to the Magix, thus, no need for a csu.
Pri WILL BE an option for an R1, but you must know what CENTRAL OFFICES the vendor can emulate.
I did a LEGEND R7 today that SPRINT was able to emulate an AT&T 4 ESS, so I set the Legend to do the same and it worked like a charm.