What is a SIM card?
The SIM (Subscriber Identification Module or Subscriber Identity Module) card – a.k.a. “smart card” – holds all of a subscriber’s personal information and phone settings. In essence, it is the subscriber’s authorization to use the network. It also holds the phone number, personal security key and other data necessary for the handset to function. The card can be switched from phone to phone, letting the new phone receive all calls to the subscriber’s number.
A SIM (Subscriber Identification Module) is the smart card that is included in every cell phone of the GSM family of networks. It’s a sophisticated computer chip embedded in a small piece of plastic about the size of a thumbnail and placed behind the battery. The SIM is present in cell phones from companies such as AT&T and T-Mobile in the U.S and many others worldwide. They are also present in smart phones like the BlackBerry and iPhone. Other cell phone providers carry the SIM only for their international roaming phones. The SIM card identifies you to your cell phone carrier (like AT&T for example) so they know your plan and services. The SIM allows you to receive wireless phone service whenever you are within coverage of your cell phone provider’s network. In addition, the SIM is an essential part of the GSM system that enables your phone to work internationally in countries where your cell phone provider allows it.
A SIM (Subscriber Identity Module) card is the heart of the GSM cell phone. It is a small chip, like the size of a dime. It is located behind the battery of most popular phones. See below “How to install a SIM card?” question. It carries vital information such as the phone number, the carrier that supplies it and accordingly the rates you will pay when placing or in some cases when receiving phone calls. It also carries the user’s identity for gaining access the network and receiving calls and also stores personal information, such as phone directory and received SMS messages.
Subscriber identity module (SIM) is a smartcard securely storing the key identifying a mobile subscriber. SIM’s are most widely used in GSM systems (Cingular, T-Mobile). This removable card is the chip inside a GSM phone with information such as the user’s phone number, phone book as well as other information relates to the subscriber is store.
