Welcome to the forum.
This type of question is asked so much...there's a forum specifically for it. Look at the very top of the page and you will see "links"...the 2nd link from the left is titled FORUM...if you click that link...scroll down the page to BLUETOOTH.
You probably won't even need to pose your question there in a new thread...just scroll down the page and see if a thread is already started/ongoing that is about the same thing you asked.
TIP: you might want to really consider adding your model/model year/build date in a permanent signature...or add it where it appears in the upper right of your posts. This information helps us to help you better by giving us an idea of how to answer your questions by already knowing what engine, transmission, change date during the production run from 1999-2006, etc. If diagrams or part nbrs are required to answer you or give suggestions...then we don't have to pose a question then wait for your answer to then go and search for the information to reply back. It also helps others that may find your thread in the future, they can tell if the info in the thread applies to them by knowing that your X5 is configured the same way theirs is...or if it falls within the same production time frame etc.