This may be a dumb question but I am curious if it would work. If AT&T has not yet released the Denim update for my 635 but I have unlocked the phone, can I insert a sim from another carrier (from another country) which has released it in order to update without waiting for AT&T? I do not know if anyone else has tried this or if I would need to flash a non carrier based rom in order to make this work.