What Is a GSM SIM Card?

SIM card is the abbreviation of (Subscriber Identity Module). It is also called smart card and subscriber identity card. GSM digital mobile phone must be installed with this card before use.

SIM GSM card

SIM GSM card

SIM card is the abbreviation of (Subscriber Identity Module). It is also called smart card and subscriber identity card. GSM digital mobile phone must be installed with this card before use.

It stores digital mobile phone customer information, encrypted keys, and other content on a computer chip, which can be used to identify the GSM network customer, and use the SIM card for the voice information of the customer during the call, completely preventing parallel Eavesdropping with the call, and the production of the SIM card is strictly in accordance with the GSM international standards and specifications, thereby reliably guaranteeing the normal communication of the customer.

The SIM card you got when you first entered the network is a large card, and the small card is embedded on the large card. Nowadays, small cards are commonly used in mobile phones. You can remove the small card from the large card and use it. The size of SIM card is 54mm × 85mm (standard size for credit card) and the size of small card is 25mm × 15mm (smaller than ordinary stamp)

In fact, the small card is the one with the chip on the big card. What really works on the "big card" is the "small card" on it. At present, the popular style in China is "small card", and small cards can also be replaced with "big card" (a Cato is enough). "Big card" and "small card" are applicable to different types of GSM mobile phones. Earlier models such as Motorola GC87C, 308C and other mobile phones used "big card", and the new models basically use " Small card".

The application of the SIM card in the GSM system separates the card from the mobile phone, and the SIM card uniquely identifies a customer. A SIM card can be inserted into any GSM mobile phone, and the communication fee generated by using the mobile phone is recorded on the customer account uniquely identified by the SIM card. The SIM card capacity is 8K, 16K, 32K, 64K, and the large-capacity SIM cards above 16K are collectively referred to as multi-function STK cards. ^[1]

GSM basic telecommunication services

WIB and STK applications

OTA function

16K, 32K capacity optional

Supports China Telecom's large-capacity phonebook and other extended applications

Telecom smart card field, including SIM card, UIM card, USIM card, PIM card, IC phone card, etc. Mobile phone SIM card meets various STK / UTK / PTK / WIB / OTAII / JAVA and other functions Identity card, with the complete functions of PHASE II SIM card, built-in COMP128 multiple versions of authentication algorithms, support for networks such as GSM / DCS1800, support for data protection, enhanced rate, anti-cloning, etc. It is safe, efficient and flexible. Suitable for SIM cards, prepaid cards, stored-value cards, data cards, mobile phone test cards, etc. of various capacities.