So a few months ago I sold my Nokia N8 and Nokia N900 to buy the Nokia N9 and the Nokia Lumia 900. I am using the At&t locked Lumia 900, I tried contacting AT&T to unlock it for me like they've done for my other phones but they directed me to Nokia and Nokia directed me back to AT&T, eventually I contacted a sales rep on Ebay who told me it can not be unlocked for 9 months. So I turned to third party websites who have successfully unlocked the device for others. They charge anything from $8 - $60 from the various services I've seen. Does anyone know how to do this on their own, such as deleting the firmware and installing a custom firmware or something like that?