I have an 01 X5 4.4i with the CPT9000 system, but when I bought the car the phone was missing. Not a huge deal since I got the car at a steal price. But I want to know if I can just buy a phone from the dealer, and put it in, but what do I do after that? Do I need to hook it up with a service company like T-mobile or Verizon etc................ Or what about this Upgrade you guys are talking about, can I just use this? Can someone Help me?.. Thanks...