Warning: Do not enter any wrong unlock unlock codes on your Sony ST21i mobile phones. If you enter over a certain amount of wrong unlock codes on your mobile phone, your phone may get hard locked and sometimes become unusable.1 - Switch ON your Sony ST21i without a SIM Card.
2 - Compose :
*#7465625*12*CODE#.
CODE: The unique unlock code for your Sony ST21i.
Each Sony ST21i mobile phone has an unique unlock code. You can buy the unique unlock code for your Sony ST21i mobile phone at www.mobileunlocksolutions.com.