What does the mobile SMS card mean?

Writing a card by SMS means writing a card by SIM card (storing user-related data).

The data stored on the SIM card includes:

1, fixed storage data. This kind of data was written by SIM card center before I sold it, including International Mobile Subscriber Identification Number (IMSI), Authentication Key (KI) and so on.

2. Relevant business codes, such as personal identification number (PIN) and unlocking code (PUK).

2. Temporarily store data about the network. Such as location area identification code (LAI), mobile subscriber temporary identification code (TMSI), etc.

Extended data:

SIM cards can be divided into three types according to their size:

1, SIM standard card: the size is 25mm×15mm× 0.8mm. ..

SIM card is an application in GSM system, which separates the card from the mobile phone and uniquely identifies a customer. The SIM card can be plugged into any GSM mobile phone, and the communication expenses generated by using the mobile phone are recorded in the customer account uniquely identified by the SIM card.

2.MicroSim: commonly known as small card, with the size of12x15mm× 0.8mm. ..

MicroSIM card, also known as 3FFSIM card, is the third type of SIM card, which is 52% smaller than the size of SIM card.

3. Nano-size:12.3mm× 8.8mm× 0.7mm. 。

The 4FF standard SIM card was first proposed by Apple and submitted to the European Telecommunications Standards Institute (ETSI). This NanoSIM card is one third smaller than MicroSIM card and 60% smaller than ordinary SIM card.

Baidu encyclopedia -SIM card