LG G1500 User Manual page 25

The PUK2 code, supplied with some SIM cards, is required to
change a blocked PIN2 code. If you lose the code, also contact your
service provider.
The security code protects the unauthorized use of your phone. It is
usually supplied with the phone. This code is required to delete all
phone entries and to activate "Factory reset" menu. The default
number of Security code is " ". You can also change it in
Security menu.
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