I would not be surprised that advanced nation-state space SIGINT has that capability for quite some time.

Only if they knew the number I guess and could ping it and look what transmitter answered. After multiple pings you could probably narrow it down a lot from all the other transmitters. But then again, if they know your number there might just be some Google or Apple API responding with a GPS reading. E.g. Google stores most peoples position anyway in their Maps SaaS.

But with this every shady US authority can map each phone number to a location. I assume that the cell phone reports its number to a tower or at least some unique id?

I really hope "Linux phones" starts to become practical so we can opt-out of all these shenanigans. And I am not even on a Washington shit list.

5G is a godsend for them because it requires many small cells.

On the other hand, that also enhances the accuracy of things like GPS. I feel like if you combine Galileo + 5G + WiFi sourcing you might get ridiculously accurate.

5G can (and usually does) run on practically the same frequencies, the same towers, the same grid sizes that LTE operates on.

Phones have been using tower location for more accurate and rapid location for decades. Some of the first standards came in 3G networks.

I am aware of A-GPS.

And the providers in my country have complained about having to place many more towers for 5G, so yeah.

It’s very easy to follow the logic - denser cells allow for more accurate triangulation.

That’s specific to mmWave though right?