A minimum amount of bands? Verizon's Upper 700 C band 13, overburdened in most markets; AT&T's Lower 700 band 17, overburdened in most markets, Sprint's Extended PCS band 25, overburdened in many markets, and T-Mobile's AWS band 4, starting to slow down in a number of markets.
Wow, that looks very counter intuitive to me.
Sprint has 3 LTE bands it's deploying on, AT&T, 4 or 5, Verizon, 4, and T-Mobile, 3, and working on a 4th with LAA.
For truly universal devices, there would have to be 10 or more LTE bands per device, for just the U.S. market, not counting international roaming.
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