I think the TCU I have is for the SA 638 professional phone

Single parts, SA 638, centre console BMW 3' E46, 330Ci (M54)

This uses bluetooth to talk to the handset, but its a non "headset" - Bluetooth to the phone system (I think), rather something proprietary system to connect to the cordless phone in the car, basically a second generation of the BIT II system, but this time using Bluetooth instead of DECT. SO basically a paper weight without the rest of the console bits and handset.

I have read this (well implied this) here:
Bluetooth Availability - Tech Update - 5 Series Forums

I think its been a waste of time and money