Indoor Positioning System

A method of operating an indoor location services system includes providing a calibration beacon signal from a calibration device at a number of calibration locations, measuring a received signal strength of the calibration beacon signal at each one of a number of receivers for each one of the number of calibration locations, measuring a received signal strength of a beacon signal provided by a locatable device at each one of the receivers, and estimating a location of the locatable device based on the received signal strength of the beacon signal at each one of the receivers, the received signal strength of the calibration beacon signal at each one of the receivers for each one of the calibration locations, and a location of each one of the receivers.