The PUK key is known from cell phones and electronic ID cards, among other things. If, for example, the personal identification number (PIN) is entered incorrectly several times in a cell phone, an error operation counter registers the incorrect entries and blocks further entries of the personal identification number (PIN) after a preset number of incorrect entries. The block can only be removed by entering the PIN Unblocking Key (PUK), also known as the Super PIN, and entering a new PIN number.
The PUK number is a multi- digit sequence of numbers. If it is entered incorrectly several times, it is blocked. In this case, a new SIM card must be requested from the network operator or an activation must be applied for.