your phone prompts you to enter a Personal Unlock Key (PUK), an eight-digit number. This number is located on the packaging your SIM card came in. If you don't have the box, contact your carrier ...

The SIM card has important information stored on it, such as your unique identifier that connects you to a specific network, your phone number, and an authentication key unique to your SIM card.

[Jason Gin] wanted to reuse the SIM card that came with a ZTE WF721 wireless terminal he got from AT&T, but as he expected, it was locked to the device. Unfortunately, the terminal has no function ...