A SIM (Subscriber Identity Module) card is a printed circuit board, a little smaller than a postage stamp. The module goes into a slot at the back of your cell phone as you take off the back cover. The SIM card is the module which renders your cell phone intelligent, and enables you to make and receive calls and send SMS messages to your friends, associates and family back home. It has a microprocessor circuitry with memories and holds your unique information, such as, identifying you as a cell phone service subscriber. It holds your subscription information, your SIM card number, the International Mobile Subscriber Identity (IMSI) of your mobile phone and other security details.
international SIM