Bellow is shown the exact method to insert the unlock codes for LG KF755/ KF755d Secret
1.Switch ON your phone with an non-allowed SIM card (from a different carrier)
2.Then compose 2945#*755# or 2945#*750#
3.Enter NCK and press OK.
Need an LG KF755/ KF755d Secret unlock code,can get it for less that 3$ :Lg unlock codes