If u Enter This Code Thrice Time Wrong. It Ask For PUK(Personal Unblocking Key) Code.
if u enter this code wrong 10 time your SIM is blocked.
so when u enter the restriction code three times it ask for PUK code u get this puk code by contacting YOur operator(Customer Care).
then they ask u the phone no or 16 digit no Printed on your sim card then they give u the PUK Code.
when u enter the puk code your phone ask for new Pin or new restriction code.