1. A method for determining a location of a tag, comprising: receiving, at each detector of at least one of a plurality of first detectors and a plurality of second detectors, a device transmission periodically transmitted from the tag, where the plurality of first detectors are disposed in proximity to a passage at which a person can transition from a first demarcated area to a second demarcated area, the plurality of second detectors are disposed within the first and second demarcated areas, and the passage is sub-divided into a plurality of zones; determining, by at least one of the plurality of first detectors and the plurality of second detectors, Received Signal Strength Indictors (“RSSIs”) for the device transmission received thereat; determining, by a computing device, a probable location of the tag within the passage, first demarcated area or second demarcated area using the RSSIs and relationships between the RSSIs; determining a first likelihood value indicating the likelihood that the probable location is correct; and determining an estimated location of the tag within the passage, first demarcated area or second demarcated area based on the probable location when the first likelihood value meets a first criteria.