Part 84116952218 (Telematics Control Unit) was found on the following E53 vehicles: E53 X5 3.0i SAV, M54, USA (FA53) : Single parts SA 639, trunk

For vehicles with
Preparation f mobile phone cpl. USA/CDN S639A=Yes Adapter Snap-In


You have S639A not

S644A=Yes Preparation f mobile phone w Bluetooth
S633A=Yes Preparation, mobile phone, Business


Where
S639A = COMPLETE PREP. CELLULAR PHONE USA/CDN Preparation f mobile phone cpl.
USA/CDN

So you may have been prewired, and the TCU fitted to make it compatible with a Snap In adaptor. Why the BT doesn't work is a mystery. Take it apart and post photos of the radio connected to the cream antenna. Make sure the writing on the chips is visible. You may find the radio is under a sheilding can.