Insert a SIM Card from a different carrier than the one your handset is using. When power up is complete the handset will display a message like those below if it SIM locked: Enter Subsidy Code, Enter Unlock Code, Incorrect Sim Card, Insert Correct Sim Card, Invalid Smart Chip, Phone Restricted, Sim Network Unlock Code, Sim Network Unlock Pin, Special Code Required, Wrong Sim Card, Network Lock Control Key, Sim Password, Incompatible Sim, Enter Subsidy Pin