Originally Posted by Brian-bmw

There are two different systems, TCU or ULF based. They have some cost and feature trade-offs. Here is a great post that lists the key parts for both types of installations. Much of the additional installation and part selection details are located in posts both in this forum and the forum referenced by this post.
Consolidated Bluetooth ULF and TCU Parts Lists…

All U.S. specification and most other international market cars are pre-wired for phone. I think that the phone module is located in the compartment with the CD changer, nav computer, and DSP amp in the X5. I think that it is only the radio and Sirius module located near the spare.