What is the subscriber identity module?

Subscriber identity, otherwise known as SIM, is a circuit that stores network information and subscriber information for mobile devices such as mobile phone or computer. The subscriber identity module operates to uniquely identify individuals in a particular network and verify its right to use the network along with other specific information, such as the passwords and services to which the user has subscribed. Without a functional subscriber identity module, the network capabilities of the associated device are crippled. It provides them with access to the theater, the mobile network they connect to. It does this by saving integrated card identifiers (ICCID) identifiers. Integrated circuits identifiers are included in the network carrier identifier - such as a specific mobile phone company - Coukod NTRE for the end user region, end user account number and control numbers. The control digit is a verification number, similar to the security code on the back of the creditcards.

In addition, the SIM also contains a verification key for a specific mobile network that the end user is associated with. It's a bit like a wireless security code for wireless networks, which ensures that not only anyone can't jump and steal the bandwidth width. Using a combination of codes such as ICCID and authentication code, ensures that SIM cards are not easily attacked.

The Subscriber Identity Module Card comes in three main sizes. The first size is roughly the same size as the credit card; But as the mobile device continues to reduce the size, this form factor has been largely abandoned. The most common SIM card types are mini and micro Sims today. Mini Sims is only 25millimeters (just below the inch) by 15 millimeters (about 0.6 inches) in size. Micro Sims are only 15 millimeters (0.6 inches) to 12 millimeters (about half an inch), which is useful for the smallest types of mobileelectronic devices.