Hi,there is restriction code and security code for mobile..Restriction code means codes used to unlock your mobile from network lock and it will be some set of numbers where you have to enter in your mobile to unlock your mobile with some procedure..and security code is that which is used to lock your mobile from use of other persons and if you forget it,then you can try "0000" or "1234" as default code (if mobile is nokia) or you can get it from online providers...if you want restriction code for your mobile then try from classicunlocking to get codes to unlock your mobile...