The 04 X5 does not have bluetooth from the factory. BMW wanted to have bluetooth and put in some of the parts but never got it to work until 05 X5.

You need a bluetooth retrofit kit such as the ones on www.bimmernav.com

Install is very simple and straight forward. It just requires that you remove/replace the old module and add the pairing button under the arm rest. Here are details on how to install

http://www.bimmernav.com/BMW_X5_Blue...tructions.html