Fun story: I purchased several wireless access points from an eBay seller, years back, and when I brought them online, our geolocation services on all our phones thought we were several hundred miles away from where we lived for many months. I assume the bssid data was feeding the incongruency.

After a few months, however, whatever database was feeding our devices with bad geolocation data, was updated, and we were once again “located” in the correct spot.

The accuracy of these systems is incredible, it will actually use, not only your own bssid, but also that of complete strangers to try to figure out where you are without turning on GPS. If your personal bssid is weak but your neighbors bssid is stronger, it will adjust your position based on the relative signal strength of each bssid that is detected. In the same way triangulation works with most radio signals.

I’ve seen such systems estimate, with a fair amount of accuracy, client location data on a floorplan where there are a few dozen access points in the space… So it works both ways. In that case I was part of a team at a job where the client had a couple thousand square feet of floor space, and about 12-15 access points to blanket the space in coverage. We could, with some degree of accuracy, follow the location of someone as they moved through the space; knowing where they spent most of their time, and what services in the space were utilized by the guest.

… It was a mid-sized airport.