Abstract: A method and system for detecting a transition in positioning state of a mobile device relative to an indoor facility. The method, executed in a processor of the mobile device, comprises monitoring, based at least in part on global positioning system (GPS) data, for a positioning state of the mobile device as one of an indoor and an outside location relative to an indoor facility, determining a set of probabilistic weightings for respective ones of ambient data and the GPS data, the ambient data including one or more of received signal strength data, signal connectivity data, magnetic data, ambient lighting data and barometric data, and detecting a transition in positioning state of the mobile device from one of the indoor and the outside locations to another of the indoor and the outside locations when a weighted sum value based at least in part on the set of probabilistic weightings is one of above and below a predetermined state transition value.