Your SIM card will become blocked with three incorrect PIN entries.
Cingular SIM cards, now AT&T SIM cards since the merger with BellSouth in 2006, can become blocked as a security precaution. SIM cards are protected by a four- to eight-digit PIN that must be entered correctly before the phone can be used. AT&T's default SIM PIN code is set to "1111" but can be changed by the user. After three incorrect entries of a PIN, your SIM card will become blocked. You can unlock it in a few steps.
Instructions
1. Obtain the PIN Unlock Key (PUK) code for your device by calling AT&T customer support at 1-800-331-0500. You need to verify your account details before the code is released to you. If you have your account registered on AT&T's myWireless website, you can also get the PUK code by logging in and clicking the "Unblock SIM Card" link on the "Phone/Device" page.
2. Use your phone's keypad to type in the eight-digit PUK code, then press "OK."
3. Type in a new PIN code when prompted. The new PIN should be four to eight digits. Press "OK."
4. Type the PIN again to confirm. Press "OK." Your SIM is now unlocked, provided all codes were entered correctly. Repeat the steps if you receive an error message and verify the PUK code if necessary.
Tags: become blocked, card will, card will become, entered correctly, incorrect entries, three incorrect