Our 2005 X5 came with Bluetooth. I don't recall if it was part of the Sport package, but we definitely did not add it as an individual option.

Simple thing to do is try pairing your cell phone to it when you turn on the X5. The BMW bluetooth goes into pairing mode for 1 or 2 minutes. The caveat is that BMW bluetooth is not 100% compatible with all phones. For example, we had a Motorola Droid X2 which would not work with the bluetooth, however 4 other cell phones work fine. Motorola support said the phone was not compatible with BMW. Upgraded to Droid Bionic which works fine.