What is the use of sim card lock?

SIM card lock is used to prevent others from making calls or using cellular data; one of the most important functions of the SIM card is authentication and encryption. When a user moves to a new area to make or receive calls, the switch must Authenticate the user to determine if the user is legitimate.

The operating environment of this tutorial: MIUI 13 system, Xiaomi 12 mobile phone.

What is the use of sim card lock

The function of locking the SIM card on a mobile phone is to prevent others from using it to make and receive calls or use cellular data.

The PIN code of the mobile phone is a security measure to protect the SIM card and prevent others from stealing the SIM card. If the power-on PIN code is enabled, then a 4-8 digit PIN must be entered every time the phone is turned on. code. When the PIN code is entered incorrectly for more than three times, the card will be automatically locked for protection. To unlock, you need to use the PUK code to call the operator's customer service.

One of the most important functions of the SIM card is authentication and encryption. When the user moves to a new area to make or receive calls, the switch must authenticate the user to Determine whether the user is a legitimate user. At this point, the SIM card and the switch use the authentication algorithm at the same time to calculate the authentication key and 8-bit random number. If the calculation results are the same, the SIM card is recognized. Otherwise, the SIM card will be rejected and the user will not be able to make calls. The SIM card can also encrypt conversation sounds using encryption algorithms.

The PIN code of the mobile phone is a security measure to protect the SIM card and prevent others from stealing the SIM card. If the power-on PIN code is enabled, a 4-8 digit PIN code must be entered every time the phone is turned on. When the PIN code is entered incorrectly for more than three times, the card will be automatically locked for protection. To unlock, you need to use the PUK code to call the operator's customer service hotline.

Do not try to guess the SIM card PIN or PUK code. Wrong guessing may cause the SIM card to be permanently locked, and you will need to obtain a new SIM card. If your device asks for a PIN or code and you don't know the information, here's what you can do:

If you're not sure which carrier to contact, remove your SIM card and look for the carrier on the card Trader's name or logo.

If the SIM card cannot be unlocked using the SIM card PIN or PUK code, or a "PUK exhausted" warning is displayed, you need to apply for a new SIM card.

Extended knowledge

SIM (Subscriber Identity Module) card is an IC card held by mobile users of the GSM system, called subscriber identification Card. The GSM system identifies GSM users through SIM cards. The same SIM card can be used on different mobile phones. GSM mobile phones can only be used on the network after inserting a SIM card [1] .

The SIM card is the key for GSM mobile phones to connect to the GSM network. Once the SIM card is pulled out from the mobile phone, the mobile phone will not be able to enjoy various services provided by the network operator except for emergency calls. In addition to being used as keys, SIM cards also provide users with a lot of convenience. Users only need to insert or embed the SIM card into any GSM terminal to achieve communication. The SIM card also manages a lot of information provided to users and can be used to store short messages, especially those received when the user does not turn on the phone or is away.

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