Subscriber identity module
The interaction of the cellular subscriber and the equipment identity is a fundamental function of the subscriber identity module (SIM). The SIM contains the international mobile subscriber identity (IMSI) that uniquely identifies the owner of the service. The service ownership concept is key since in the GSM world the handset is merely a piece of equipment that users can share. A user could put her SIM in a friend’s phone and get all of her services. The IMSI identifies the subscriber to the system, has the secret for authentication, and any other pertinent information about the subscriber’s services. The SIM card itself can also be password protected so that if stolen, it cannot be easily used. In fact, there is practically no theft of GSM SIM cards since they are worthless to the thief.
|<mp3>http://hill-vt.com/podcast/tHAWT/tHAWT_071709.mp3%7Cdownload</mp3> | SIM|