The BMW ULF is the factory bluetooth control unit that interacts with the vehicle i-bus system allowing integration of audio, display and phonebook functions through the car systems including steeringwheel controls, OBC display on the dash and display on the nav screen.

Advanced Autovations re-sells the BMW ULF unit with the proper wiring harness/adapters to allow installation in pre-bluetooth model years (I put their kit in my 2001) and vehicles without originally installed bluetooth.

Automotive Data Research has packaged a third party (Parrot CK3000) bluetooth unit with a wiring harness adapter for installation in the BMW. I believe that the functions are limited to audio controls only, no phonebook or display functions.

At least this is as much as I can figure out from my experience.

Dennis