Everything about Subscriber Identity Modules (SIM) Card Technology

Subscriber identity module, commonly known as SIM card, is an integrated circuit that can be used to store the international mobile subscriber identity number and its related key that can be used to identify and authenticate subscribers on cell phones. It is possible to store contact details on many SIM cards. These cards are always used on GSM phones; for CDMA phones, they are required only for LTE-capable handsets. These cards are also used in satellite phones, smartwatches, cameras, or computers.

The SIM circuit plays an important part in the function of a universal integrated circuit card physical smart card that is made of PVC with embedded contacts as well as semiconductors. SIM cards are generally transferable between different mobile devices. The first universal integrated circuit card smart cards were big in size; however, the sizes were reduced several times over the years, keeping electrical contacts the same, so that a larger card could be cut down to a smaller size.

A subscriber identity module or SIM card includes a unique serial number (ICCID), international mobile subscriber identity (IMSI) number, security authentication as well as ciphering information, temporary details related to the local network, a list of the services the user has access to, along with two passwords: a personal identification number for ordinary use, and a personal unblocking key for PIN unlocking. In Europe, the serial SIM number or SSN is accompanied by an international article number or a European article number needed when registering on line for the subscription of prepaid cards.

SIM cards can be identified on their individual operator networks by a unique IMSI. Mobile network operators connect phone calls and interact with their market SIM cards with the help of IMSIs. The SIM card formats are:

• The first three digits that signify Mobile Country Code (MCC)
• The next two digits explain the Mobile Network Code (MNC). These codes are allowed by E.212, but they can be used in the United States and Canada.
• The next digits signify the mobile subscriber identification number (MSIN). There are 10 digits that can be fewer in the case of a 3-digit MNC or if national regulations explain that the total length of the IMSI should be less than 15 digits.
• Depending on the country, the digits are different.