A method of disambiguating a location of a mobile station within a structure includes: obtaining, at the mobile station, regional pressure indications and corresponding region indications indicating regions within a structure that are vertically displaced with respect to each other, each of the regional pressure indications indicating atmospheric pressure information associated with the corresponding region; determining mobile station pressure information associated with a present location of the mobile station; comparing the mobile station pressure information with the regional pressure indications; and based on the comparing, determining in which of the regions the mobile station presently resides.