this post was submitted on 19 Jan 2025
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Today I Learned

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Trope: Police have to keep bad guy talking on the phone long enough to trace them and find their location. Professional bad guys hang up right before it triangulates their coordinates.

Apparently, Hollywood's been getting this inspiration from a pre-digital age when they use this trope in movies. See link for more info. It's just funny that most of the "tracing the call" scenes I've seen are definitely after the 2000's.

Another link: https://slate.com/news-and-politics/2002/10/how-hard-would-it-be-to-trace-the-sniper-s-phone-calls.html

A fun gif: https://i.gifer.com/9QtC.mp4

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[–] Kyle_The_G@lemmy.world 20 points 1 day ago (1 children)

Everyone has a GPS on their phone anyway I'd imagine they just use that lol.

[–] TachyonTele@lemm.ee 21 points 1 day ago (4 children)

They don't even need gps. They can just track you by the cell towers your phone automatically connects to.

[–] jagged_circle@feddit.nl 1 points 1 hour ago

That only works if you use connect to cell towers. Dont use a SIM. Leave it in airplane mode. Use WiFi.

[–] Fondots@lemmy.world 38 points 23 hours ago (3 children)

I work in 911 dispatch, so I have some relevant knowledge here

Cell tower triangulation is our bread and butter for locating a cell phone. It also kind of sucks.

With triangulation we get a set of latitude/longitude coordinates, a "confidence factor" which is a radius in meters around that point that basically shows you the potential error, and a "confidence percentage" which is how confident the cell provider is in that information (it's 90% I've literally never seen it be any number other than 90%)

The confidence factor depends on a few different things- geography, how many cell towers the phone is able to connect to, if you're inside/outside, etc.

The policy where I work is if it's within 300 meters we can enter the call as normal and send cops, fire, EMS, or whoever out to look for the emergency if we get no other location info from the caller. More than 300m and it's usually getting bumped down to an information call, cops will still go to check it out but even 300m is a pretty big area to have them check and can include potentially hundreds of houses, apartments, businesses, etc.

Usually we can get that 300m accuracy, but not always by a longshot, I sometimes see them in the thousands of meters which is basically useless. It also takes about 20-30 seconds to refresh so it's not a live location, and if they're, for example, in a moving vehicle, they can be a pretty significant distance away in 30 seconds, let alone in the several minutes it takes responders to arrive.

And once we're off the call, we don't get any further location updates. If we want to ping the phone again, that involves calling the phone company and faxing them paperwork or something like that (it's handled by our supervisor so I'm not directly involved in that part of the process) I think it normally ends up taking like 10 or 20 minutes for us to get a ping that way, and then it's only 1 ping at a time and they're going to be spaced out about that far or further.

Handset gps based location is generally more accurate (although occasionally it does happen that it's less accurate than the triangulation) but we don't necessarily get it on every call, it's still kind of a hacked-together system at a lot of dispatch centers and it doesn't always integrate well with the other software. It does update much faster, and we usually continue to get updated locations from it for maybe a couple minutes after we hang up.

We don't really have any way that I'm aware of to request a gps based ping on a phone we're not on the line with.

I'm sure the feds have some back doors and extra tools at their disposal that we don't have at a county 911 center, I really can't speak to that. I doubt they're able to get a much more accurate triangulation ping than we are, that seems like a pretty hard limitation of the technology to me.

[–] dingdongitsabear@lemmy.ml 2 points 7 hours ago* (last edited 7 hours ago)

calling the phone company and faxing them paperwork

doing WHAT the fuck now?!?

~~on a more serious note, can you elaborate on the thing where you, a call receiver, have access to the GPS on the caller's phone? like, how?~~ asked and answered, still don't understand how that happens.

[–] TachyonTele@lemm.ee 4 points 22 hours ago

That's really cool. Thank you so much for sharing!

[–] Tiger@sh.itjust.works 2 points 19 hours ago (1 children)

I wonder how they get GPS info through a call, hmm.

[–] Fondots@lemmy.world 6 points 19 hours ago

It goes through your phone's data connection. That's part of the reason we don't get GPS info on all calls, no data, no gps. If you call from a deactivated cell phone that can only call 911 for example, since you don't have data we don't get that gps data(or your emergency contact or medical info if you've filled that out on your phone)

[–] Kolanaki@yiffit.net 10 points 1 day ago (2 children)

They don't even need that! They can triangulate from Bluetooth and wifi radios as well.

[–] darkpanda@lemmy.ca 14 points 1 day ago (1 children)

They don’t even need that anymore either, ‘cause they can just use the chips and magnetofluids they’ve injected into everyone via vaccines. So outdated.

[–] TachyonTele@lemm.ee 1 points 20 hours ago

Well, i mean... Duh

[–] TachyonTele@lemm.ee 9 points 1 day ago (2 children)

I know for sure that cops can use cell towers. Are there any examples of using Bluetooth and wifi?

I believe you. Im just curious.

[–] BigDiction@lemmy.world 8 points 1 day ago

I’ve heard of a technique to track specific vehicles based on the tire pressure monitoring system in newer cars that use Bluetooth. I kinds of assume anything wireless that broadcasts a unique ID can be tracked somehow.

[–] Kolanaki@yiffit.net 8 points 1 day ago* (last edited 1 day ago) (2 children)

It is how phones without GPS hardware get your location for things like Maps and whatnot. If you've ever had it ask you to turn BT on for better accuracy, that's why; it just opens up more connection points to triangulate position.

And, just triangulation itself works by doing math on the signal range between a minimum of 3 points of connectivity. It could be done with any wireless communication system.

[–] jagged_circle@feddit.nl -1 points 1 hour ago (1 children)

This isn't a risk if you dont have gapps installed

[–] Kolanaki@yiffit.net 1 points 58 minutes ago* (last edited 57 minutes ago)

It's not limited to just Google. The apps don't even matter. The phone just needs to be pinged from 3 different locations and you can find its position.

https://en.m.wikipedia.org/wiki/Triangulation

[–] TachyonTele@lemm.ee 1 points 20 hours ago

Interesting. I've never been able to get any map app to know my location without cell data and turning Location on.

[–] Psaldorn@lemmy.world 5 points 22 hours ago

I recently worked with this data and it's actually really rough. Different standards for cell tower IDs, overlaps and same tower different tech (4G/5G/NBIoT etc)

Government's would have better access but fit commercial use is not fun (for tracking your own SIMs, not other people's)