Well nowadays you individually track by using mac addresses and other network information from the devices within range. Cisco has some creepy real time maps of your location with each person walking around and all their previous visits etc
Saw a system like this at a Podunk, nowhere, USA police station over a decade ago. It had high fidelity maps of peoples comings and goings based on Bluetooth and WiFi MAC IIRC. And some kind of API backend to look up identity based on those identifiers, not sure to who.
You could for example flag a location (house) and get a list of all of the comings and goings over the last x months, then look them up by identity. You could also flag when an individual was in proximity to another, or when someone turned on, off or switched phones.
I’m sure it amounted to illegal surveillance and would be inadmissible if any of it was done without a warrant, but it would be beautiful for parallel construction. (How is that even constitutional???)
It apparently relied on some kind of infrastructure deployment that consisted of “traffic cameras” and “satellites” ( I’m certain not of the spacecraft type) that I assume were just small receivers mounted on street lights, since the streetlights were almost completely replaced at the same time as the cameras were put in, by the same out of state contractor.
I was there to change out a bad SSD and do a RAM upgrade on one of the servers. I don’t imagine the technology has become less invasive.
If you have a phone or carry active Bluetooth devices, assume you are 100 percent tracked 100 percent of the time.
If you want to not be tracked I wouldn't even trust airplane mode. With just a SIM pinging towers already a lot can be done. With airplane mode I'm just being paranoid but I never tested radio emissions myself with it disabled so I'd just leave my phone at home if I was really worried about it.
Turning your phone off (airplane mode or power down, which sign out of networks) or lighting up a new one in the same location as an old one was turned off are treated as significant events in these systems and can be configured as an automatic flag for investigation.
If you care, slip it into a faraday bag instead of turning it off or going into airplane mode and you won’t be flagged nearly as likely. People rarely use airplane mode or turn off their phones in situations where it doesn’t provide a useful clue about activity.
There is a huge overlap between surveillance platforms and behavior analysis / data brokers.
Modern phones connect with a randomized MAC address. So yes, you can track a person around, but you will need another system (like the WiFi login page) to match MAC to identity.
