Early 04's had a Telematics/Bluetooth module that only speaks with the BMW assist.
I don't recall the exact date that 'real' bluetooth support started, but I believe it was Sept/Oct of 2004. If your build date is earlier than that, you can't pair your phone with the existing hardware.

__________________
====================================
'04 E53 X5 4.4i
'05 Mazdaspeed MX-5
'00 Saab 9-3 SE Cabrio