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by awinter-py 1455 days ago
I mean check-in technology is at least as old as dodgeball (foursquare predecessor acq by G). G + FB both have check-in based features.

gps includes altitude (albeit gps isn't that precise in cities). phone geo can use cell tower triangulation + wifi scanning, on both aapl + droid, whether or not you connect to wifi.

i.e. they have lots of ways