It seems Apple are spreading the wealth, and not becoming reliant on one supplier. Also, Verizon/Sprint and AT&T/T-mobile have always had different standards. If you think back a few years, there were two distinct models of the iPhone 4. The 4s was the first advertised as a "world phone", when one model covered everyone. Maybe there isn't room in the phones now for multiple radios. No idea really. I'll be satisfied if Telus supply me with one that will work on their network.