We need a little more info from you...

1) What kind of phone are you using?
2) A 2004 X5 most likely would not have come with a BMW BT system from the factory; therefore:
A) Do you know what kind of BT system it is?
B) Did you install the system, or do you know who did?
3) Has it ever worked?
4) Can you test it with a different phone?

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SOLD
2000 E38 750iL Highline Edition, Upgraded with the lastest 2006 X5 Electronics
MKIV Navigation, 16:9 Display, Bluetooth, TV/Video with Backup Camera, Sirius, and Aux Input