Earlier quoted context omitted.
As I understand it, no. Montana would have to be effectively regulating interstate trade since neither Apple nor Google have offices here. Plus, the whole "negotiate commerce and treaties with foreign entities" thing.
So can apple turn off all iphones in Montana in retaliation. Bet it would be easier/cheaper to cut off those customers than implement any changes. Android phone makes could follow suit
GeoIP doesn't work because carriers (especially in Montana) tend to assign IPs from surrounding states as much as they do local cities. When I'm on the cell network, I'm regularly identified as coming out of Denver. Phone number area codes are equally useless, since half the folks I know here in Montana have area codes from outside states. GPS would be the best bet, though I feel like even that would have some major caveats (the use would have to be decoupled from the location services controls/displays, something they don't do for even their own apps right now).
Also, people rely on cellphones for emergency services. A manufacturer shutting down phones would probably expose them to some serious liabilities.