You can fully-unlock your Nokia Lumia 710/800 by flashing a custom ROM (that offers such feature) to it. And to flash a custom ROM (or custom firmware, abbreviated as CFW), the bootloader of your Nokia Lumia Windows Phone must be unlocked. You can first of all check if the bootloader of your phone is locked or unlocked. Detailed procedure after the break!
Checking whether your Nokia Lumia 710 or Lumia 800 has unlocked bootloader :
- Turn the phone off.
- Press and hold Volume Up button + Power Key until you notice a short vibration.
- Plug the phone in to your computer. (running Windows)
Now, if the phone goes in the ‘USB Mass Storage’ mode, that means your phone’s bootloader is unlocked! At that point, Windows will ask you to format the memory, but don’t ever do that as it’d leave you with a broken phone.
But, if your PC detects your phone as ‘Nokia DLOAD’, that means your phone’s bootloader is locked and there’s nothing you can do right now to unlock it, as far as I know.
For your information, the aforementioned unlocked bootloaders were actually developed by Qualcomm for testing purposes. (for testing their Snapdragons inside the Lumia’s)
YAY! My phone has an unlocked bootloader! :
Take a look at this tutorial if you don’t know how to flash your Lumia.