My Friend .. You are refering to a bluetooth phones which i dont have bluetooth in my X5, its 2003 and i think bluetooth started in 2004 models ..

For the Siemens phone, i am not adding it to my car, the car comes already equiped with the Phone Kit and the wireless unit already exist .. i am just replacing the wireless handset because the old one got damaged!

And like any wireless device it has a unique frequency just like the remote control of the car, so the new handset needs to be configured to the original base in the car to have it connected through the same wireless channel and frequency .. did i explain it clearly?

Sorry for the confusion ..

Regards