The disclosure relates generally to geographic-based signal detection. One claim recites an apparatus comprising: an input for receiving a signal from a cell phone; an electronic processor for determining, based at least in part on the signal, whether the cell phone is physically located in a predetermined home area; and upon a condition of not being in the predetermined home area, communicating a machine-readable code detector to the cell phone for use as its primary machine-readable code detector to detect machine-readable code while outside of its predetermined home area. Of course, other claims and combinations are provided as well.