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Comment by paxys | Hacker News Reader

Despite all the technology in the world the majority of police work is still plain old-fashioned knocking on doors and making phone calls. People will always voluntarily give up all the information in the world to be seen as good citizens. In your friend's case I'm willing to bet that they asked the sister for the names of his close friends and acquaintances and yours matched up.

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No. They can locate anyone's phone on demand. The services that do this can generate a likely street address from GPS or tower triangulated location.

This is how many criminals now get caught while on the run. It isn't magic police work but rather the personal tracking device everyone carries. Likewise some spree killers have been tracked down by geofencing phones known to be around all crime scenes and zeroing in on the one that shows up at all/most of them.

Source?

https://www.oxygen.com/crime-news/cell-phone-data-from-lori-...

Your "on demand" makes it read like they don't need to get a warrant whereas your link describes a missing-children investigation that had already made the national news, i.e., a situation in which getting a warrant would be very easy.

I've had it used on me personally without a warrant. There are no deep controls on this tech. You just have to know someone who can do a favor.

Well, sure, but more often than not, when someone on HN gives a URL to support some point, the URL ends up not actually supporting the point. I'm curious why people do that. Why did you do it?

A warrant can be "on demand" within minutes if you can get a judge to pick up his phone.

https://en.wikipedia.org/wiki/Sensorvault is for Google, with the 3 linked sources being very fun reads.

Cell phones are only connected to 1 tower afaik. So no triangulation is possible, only the tower they are connected to, which is very broad.

That's not accurate; they get angle and time (distance) from the tower. It's a hell of a lot more precise than a circle somewhere around the tower.

https://www.ericsson.com/en/blog/2020/12/5g-positioning--wha...

Other towers can still passively track your signal. You also have to communicate with more than one tower during handoff between cells. This is a capability mandated by E911.

From https://en.wikipedia.org/wiki/Enhanced_9-1-1:

  To locate a mobile telephone geographically, there are two general approaches. One is to use some form of radiolocation from the cellular network; the other is to use a Global Positioning System receiver built into the phone itself. Both approaches are described by the Radio resource location services protocol (LCS protocol).

Look at the tower. It would have at least 3 antennas giving at least a 120 degree segment. As soon as a phone connects to another one you would have a line (or more like an ellipsoid) between the two towers. Even if the phone just lies on the desk it could switch towers, eg if the current one has too many clients, or the signal quality is pretty equal between them.

NB I worked in a such place, my phone would be in low 40-50% at the end of the work day, despite being able to endure two days easily if I would be at some other place.

Carrier aggregation is a thing since LTE-Advanced

> Despite all the technology in the world the majority of police work is still plain old-fashioned knocking on doors and making phone calls. People will always voluntarily give up all the information in the world to be seen as good citizens. In your friend's case I'm willing to bet that they asked the sister for the names of his close friends and acquaintances and yours matched up.

Sure, but that doesn't pass the smell test in this situation:

1. That's a lot of work, which would take a lot of time to do. For instance, does the sister know the OP's number. His full name? His first name? Are they going do all the work to piece together fragmentary information for a wellness check?

2. The technology exists and is widely deployed for the police to straightforwardly take a quick shortcut around all that work.

And most importantly:

3. The police said they took that shortcut.

or they just triangulated using his cell phone, it can be very accurate in urban settings

Seems like much more work. Based on the stories I've seen about these operations to track down phones over the years, it's a little more complicated

Police need a warrant to get location data from your cell phone provider. No department is bothering with that for a welfare check unless the situation is really dire, and the process still takes a while to carry out. "Where do you think your brother is?" "Oh probably at XYZ's place" is a much more straightforward and common process.

I don't know the processes in US, but in Europe I saw this in action first hand done in minutes, so I don't know.

edit: Over a stolen phone, no less, not even a person being in danger.

In the US the process is you go to the police to report a stolen phone and they say "tough luck, hope you had insurance".

I have some family who are dispatchers (not in the US), and they have the ability to immediately get location data directly from providers if they think somebody is in imminent danger. They can’t do it to track a suspect (not without a warrant), but they would regularly do it for suspected suicides, or when a caller communicated they were in danger but failed to give their location for what ever reason.

I wouldn’t be surprised if many jurisdictions around the world had similar systems.

That’s for the person who is actively calling 911 though, not a random persons phone.

In the cases I’m familiar with it was often used for other people calling in suspected suicide attempts (or other types of self harm, or drug overdoses, ect…)

I am a reporter who covers crime. Your account is 100% accurate. Federal law allows for the disclosure of customer records “to a governmental entity, if the provider, in good faith, believes that an emergency involving danger of death or serious physical injury to any person requires disclosure without delay of information relating to the emergency.” 5 U.S.C § 2703(c).

But they said themselves that they pinged his phone.

They may have done both. Or they may be lying. In most cases it's best to assume that the police won't give you any info unless they are compelled to do so (and sometimes not even then).

Police need a warrant to demand that data. Nothing stops the provider from handing it over willingly.

Hopefully this new 'the Government can't compel companies' trial shuts this down as well

https://news.ycombinator.com/item?id=36614678

Either corporations are allowed to be 'pressured' by the government or they aren't. But of course the legal system will make themselves a nice carveout for their uses like always.

It won't shut it down. The cops aren't compelling or pressuring the providers to give the info. They're just doing it.

> Police need a warrant

if the information they gather is to be admissible in court as evidence against a person. Police do not need a warrant to save the life of a person.

Seems much more likely that his sister knew the friend, and suggested he might be there? Or there was some relation to the friend to know the exact address. Unless he lived at a single-family house, it's unlikely a phone's GPS would be exact enough.

You experienced a type 0 SMS. It can wake the GPS on a modern phone and return a GPS location.

Last time I checked cell tower triangulation is accurate to between a few hundred and a few thousand feet. Cellular A-GPS can be good to within a few feet inside houses usually but often its within a few tens of feet in accuracy.

> Last time I checked cell tower triangulation is accurate to between a few hundred and a few thousand feet

That was about what LTE could do. With 4G, they got it down to 20-50 meters. Now they can do much better.

They just call the phone and the system will typically triangulate it if it rings. It's used all the time in search and rescue.

I like this idea, very human. Social engineering basically. And at the end, they are not required to tell you their method.

But they can't find a stolen bicycle with a gps tracker as the gps information 'may not be accurate'. Similar for phones. /(am in europe)

That's just it, they are doing their own thing. This is why I liked the explanation, it reflects that the police is not an organization that's somehow representing and enforcing a higher moral standard, but rather a distinct thing that has its own life and culture. And that social engineering and parallel construction are part of daily life.

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