If you have a LG Optimus 4X HD P880 and want to obtain the maximum potential from the same, then you need to unlock its bootloader.
The guide was replied from LG, containing the official bootloader unlocking procedure. I’m not sure if this will work, do at your own risk.
Official bootloader unlock procedure for LG Optimus 4X HD P880
Warning: You unlock your bootloader at your own risk and therefore you run the risk on your own of something happening during the process. I’m not responsible for any damage or brick of your device. Enjoy.
Guide to unlock 262-000 bootloader:
LG Optimus 4X HD P880 Phone Photos – LG Cell Phone Pictures
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Anyway to unlock the bootloader if you don’t have a SIM card? I use WIFI only and don’t have any SIM card in the phone.