128kusim is the third generation mobile phone card. Its 128k represents the capacity of the mobile phone card, and usim is the abbreviation of Universal Subscriber Identity Module, which means global subscriber identification card.
Demo environment for this article: MIUI12.5 system, Xiaomi 11
What kind of card is 128kusim?
USIM card is the third generation mobile phone card. 128K is the capacity of the mobile phone card. USIM is the abbreviation of Universal Subscriber Identity Module (global subscriber identification card). Global User Identity Module (USIM).
USIM card principle CPU (32-bit), program memory ROM, working memory RAM, data memory EEPROM and serial communication unit, these five modules are integrated into an integrated circuit. When the USIM card is connected to a mobile phone, at least 5 connection lines are required: power supply (Vcc) * clock (CLK) * data I/O port (Data) * reset (RST) * ground terminal (GND).
USIM card password:
The PIN code refers to the password of the USIM card, which exists in the USIM card. Its factory value is 1234 or 0000. After activating the PIN code, you must enter the PIN code every time you turn on the computer to log in to the network. The PUK code is a master key used to decrypt the PIN code, with a total of 8 digits. Users do not know the PUK code and can only go to the business hall and have the staff operate it.
When the PIN code is entered incorrectly three times, the USIM card will be automatically locked. At this time, it can only be unlocked by entering the PUK. There are 10 opportunities to enter the PUK code. Therefore, at this time, users must not touch the PUK password by themselves. After entering the wrong password 10 times, the USIM card will automatically start a self-destruct program, making the USIM card invalid. At this time, the only option is to go back to the business hall to change the card. In fact, as long as you use it carefully, PIN passwords will only protect your security.
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