Cellular Phreaking :: essays research papers

Cellular Phreaking The cellular/mobile phone system is one that is perfectly set up to be exploited by phreaks with the proper knowledge and equipment. Thanks to deregulation, the regional BOC's (Bell Operating Companies) are scattered and do not communicate much with each other. Phreaks can take advantage of this by pretending to be mobile phone customers whose "home base" is a city served by a different BOC, known as a "roamer". Since it is impractical for each BOC to keep track of the customers of all the other BOC's, they will usually allow the customer to make the calls he wishes, often with a surcharge of some sort. The bill is then forwarded to the roamer's home BOC for collection. However, it is fairly simple (with the correct tools) to create a bogus ID number for your mobile phone, and pretend to be a roamer from some other city and state, that's "just visiting". When your BOC tries to collect for the calls from your alleged "home BOC", they will discover you are not a real customer; but by then, you can create an entirely new electronic identity, and use that instead. How does the cellular system know who is calling, and where they are? When a mobile phone enters a cell's area of transmission, it transmits its phone number and its 8 digit ID number to that cell, who will keep track of it until it gets far enough away that the sound quality is sufficiently diminished, and then the phone is "handed off" to the cell that the customer has walked or driven into. This process continues as long as the phone has power and is turned on. If the phone is turned off (or the car is), someone attempting to call the mobile phone will receive a recording along the lines of "The mobile phone customer you have dialed has left the vehicle or driven out of the service area." When a call is made to a mobile phone, the switching equipment will check to see if the mobile phone being called is "logged in", so to speak, or present in one of the cells. If it is, the call will then act (to the speaking parties) just like a normal call - the caller may hear a busy tone, the phone may just ring, or the call may be answered. How does the switching equipment know whether or not a particular phone is authorized to use the network? Many times, it doesn't. When a dealer installs a mobile phone, he gives the phone's ID number (an 8 digit hexadecimal number)