An indoor location positioning system comprises at least one processor, Wi-Fi scanners, and a RSSI fingerprint database. The Wi-Fi scanners and the RSSI fingerprint database works with the processor. The Wi-Fi scanners are positioned at locations within an environment that is partitioned into interconnected zones. The Wi-Fi scanners receive anonymous probe messages from Wi-Fi devices that are present in the environment during a calibration phase of the indoor location positioning system. The RSSI values are collated to create RSSI fingerprints corresponding to the different locations respectively. One or more of the Wi-Fi scanners are used as anchor scanners to counter the difference in transmit power levels of different Wi-Fi devices that result in different RSSI fingerprints for the different types of Wi-Fi devices, wherein the RSSI value at each anchor scanner is subtracted from the RSSI values at rest of the Wi-Fi scanners to generate the RSSI fingerprint.