Of all the Nokia devices to have been graced by custom ROMs, the Lumia 900 to our knowledge remains an exception. Before one applies a custom ROM, the so-called bootloader needs to be “unlocked” (and that’s very different from SIM unlocking). We won’t get into the messy details, but that’s the gist of it and so far, the 900 has not been unlocked for loading some sweet custom work.
Now a report coming out of WinPhoneViet seems to show that the Lumia 900 can be unlocked as well, but it’s going to be way more advanced than what most users can do on a weekend afternoon. Evidently the process here requires an ATF Box, which is a physical third-party device used for flashing around Nokia phones, and taking the phone apart. Yes, you read that correctly. Throw in the fact that the info comes via a Vietnamese phone forum (for translation challenges) and this could be quite the DIY Project.
Physical bootloader unlocks are messy, to say the least. But this could be the first step in getting a software bootloader unlock and something more readily applicable for you “enthusiast” users out there.
Source: WinPhoneViet; Thanks, Tùng Hà, for the tip!