Select Service Info and then Simlock, If X is with Network and it is not 0, Switch on your phone without SIM card Compose *#*#7378423#*#*
Please make sure to check the counter of your phone: Please do not use this service for Telcel Mexico or any other network provider who delivers his phones with broken GDFS (0 Code Entry Left) or phone which has 'too many wrong codes'
NLCK4, NSLCK4, SPLCK4U, CLCK4, PCK4, ESLCK4, NLCK4U, NSLCK4U, SPLCK4U, CLCK4U, PCK4U, ESLCK4U (In this situation, please always use NLCK4U or NSLCK4U)
This service is directly from Sony database, the Unlock Code is 99.99% correct unless your IMEI is wrong, your phone is rooted or your phone is refurbished.