I can't seem to get to the bottom of the news about the T-Mobile update for unlocked iPhones or the lack of Band IV UMTS support for existing iPhones. For the T-Mobile software update, what did they actually enable? I keep seeing references to LTE, but the unlocked iPhone already supported LTE on four bands, including Bands IV and XVII, in addition to II and V. Is it some carrier setting specific to T-Mobile? Or auto-configuration of something? Also, why can't the existing iPhones that are unlocked or on AT&T be "re-flasked" so to speak to work on UMTS Band IV? They have UMTS hardware, and they have Band IV hardware, so what is stopping them from getting UMTS Band IV running? The chips seems to support everything under the sun, it's just a matter of amps and antennas, and the iPhone 5 obviously has those working on Band IV for LTE. Everyone seems so confused about these things.