SIM PIN and PIN Unlock Key (PUK) code on your Nokia Lumia 920 - Dr. Z's Blog - Site Home - MSDN Blog
A SIM PIN is a four to eight digit code that is used to prevent unauthorized use of a SIM card. The default PIN for an AT&T SIM card is 1111. A PIN Unlock Key (PUK) code is required to unlock SIM cards that have become locked following three successive in...