SIM card blocking

A SIM card can be blocked either by the user or the operator. The user can accidentally block their card if they enter an incorrect PIN code three times in a row. The card can be unblocked only with the help of a so-called PUK code. If the user enters an incorrect PUK code repeatedly, the SIM card will be blocked permanently.
The operator will block a SIM card (the access of the given SIM card to a network) if contract terms and conditions are violated or if the user requests it (for example, in case of theft).