PIN code is the personal identification password of SIM card, which is used to protect SIM card and prevent it from being illegally used. If the PIN code is enabled, you need to enter the password every time you turn it on.

Unlocking method of PIN code of vivo mobile phone: Go to Settings-Security and Privacy-More Security Settings-Set SIM card lock, open "Lock SIM card" and enter PIN code.

(Path for setting some models: Enter Settings-Security-Set SIM Card Lock/Settings-More Settings-Security)

Handling method of forgetting PIN code: PIN code is provided by network operators and consists of 4 to 8 digits. By default, the PIN code is 1234 or 0000. If you forget to change it, you can use PUK code to unlock it, but don't try it at will, because the input opportunity of PUK code is only 10 times. Once used up, you can only reissue a new SIM card in the business hall.

The PUK code can be found on the big card of the SIM card, or you can contact the customer service of the operator to which the SIM card belongs.