All I know is that some don't. I don't know brands or if there are even common modems that are filtering for this.
If you don't have a Faraday cage and cell site equipment, you're going to have a hard time verifying any of this. The modem is closed source, the SIM card is closed source, and various firmware blobs to make phones work are all closed source. I believe Qualcomm has debug interfaces on some chipsets, which might catch these messages, but verifying that they catch all use cases is impossible unless you have knowledge of the actual mechanism used (or usable) to activate the modem.
This is one of the reasons I'm hoping for the open source phone community to succeed. So far, the modem stack is usually proprietary (with hardware kill switches in the most paranoid phones), but it only takes a small group of Linux enthusiasts to actually catch the phone network in the act.
Of course, the trouble is that you'll need to be the target of government surveillance to be even at risk of any of this. If you're not a criminal or a human rights activist, the government is probably not pointing its secret spying equipment at you, and whatever criminal enterprise hacked its way into the carrier network won't either. If you are being tracked by either of those, I think developing open source modem firmware is probably the least of your concerns.
I honestly wouldn't be surprised if the standard was written to make this kind of surveillance possible and that any modem refusing to cooperate would be spec incompliant. You can read most of the 3GPP spec for free on sites like https://portal.3gpp.org/ but I don't have the time or interest to dig through the unreadable stream of abbreviations and industry terms to find out.
It's all rather pointless anyway when 5G and to an extend 4G can geolocate you about as well as GPS can, barring reflections and such.
> If you're not a criminal or a human rights activist, the government is probably not pointing its secret spying equipment at you
If there's one thing we know for certain about the US and domestic spying it's that they're targeting literally everyone. They were caught copying all internet traffic going over the AT&T backbone in the early 2000s and decades later Snowden showed us they never stopped pointing their secret spying equipment at us. The best you can hope for is that if you don't become an activist or commit enough crimes they won't pay much attention to the massive and ever-growing troves of data they have on you personally.
Agreed – it's not really a personal concern I have (I have no illusions about the chances that none of the apps I grant location access to are selling it to the highest bidder), but I'm still curious. I can also imagine some legitimate use cases, such as pinging the location of somebody that had an accident and is possibly unable to call 911 themselves.
And same here – I've read a few of the 3GPP specs, but they make legalese sound like plain English, and of course never tell the full story including actual manufacturer decisions.
> And same here – I've read a few of the 3GPP specs, but they make legalese sound like plain English, and of course never tell the full story including actual manufacturer decisions.
They are technical standards designed to ensure interoperability (though not always successfully — cough VoLTE cough) rather than exhaustive guides on how to implement features. They have been developed over a long period of time and have become quite complicated to read, especially if you are not familiar with the specific nomenclature. However, with enough time and willpower you can make sense of them quite quickly.
PS. The software behind these standards is probably the most complex we have in the world. At least I am not aware of anything else that is as complicated.
> This is one of the reasons I'm hoping for the open source phone community to succeed. So far, the modem stack is usually proprietary (with hardware kill switches in the most paranoid phones) [...]
This is very unlikely to happen, primarily because certifying these modems is extremely expensive. I doubt any commercial vendor (e.g., a phone manufacturer) would commit the necessary resources to support them. Modern modems are also highly complex; they not only support various radio technologies but also incorporate numerous offloading mechanisms and a range of proprietary communication methods with telecom operators (e.g., VoLTE). Furthermore, the firmware must be carefully optimized for the hardware, so unless you have access to the complete package, this will likely remain confined to amateur circles.
> I honestly wouldn't be surprised if the standard was written to make this kind of surveillance possible and that any modem refusing to cooperate would be spec incompliant. You can read most of the 3GPP spec for free on sites like https://portal.3gpp.org/ but I don't have the time or interest to dig through the unreadable stream of abbreviations and industry terms to find out.
The standard is written to accommodate the most prevalent use cases. Given the ongoing efforts to improve security and address known vulnerabilities, I highly doubt it was written with bad intentions. However, that does not mean they will catch everything, nor does it guarantee that they will always prioritize stronger security over better usability - whether for network operators or end users.
Also worth noting that if the carrier is cooperating then you can do better than static snapshots. Tracking signal strength of a target moving between towers will give you quite a precise historic path (within a few seconds or minutes depending on velocity).
If you don't have a Faraday cage and cell site equipment, you're going to have a hard time verifying any of this. The modem is closed source, the SIM card is closed source, and various firmware blobs to make phones work are all closed source. I believe Qualcomm has debug interfaces on some chipsets, which might catch these messages, but verifying that they catch all use cases is impossible unless you have knowledge of the actual mechanism used (or usable) to activate the modem.
This is one of the reasons I'm hoping for the open source phone community to succeed. So far, the modem stack is usually proprietary (with hardware kill switches in the most paranoid phones), but it only takes a small group of Linux enthusiasts to actually catch the phone network in the act.
Of course, the trouble is that you'll need to be the target of government surveillance to be even at risk of any of this. If you're not a criminal or a human rights activist, the government is probably not pointing its secret spying equipment at you, and whatever criminal enterprise hacked its way into the carrier network won't either. If you are being tracked by either of those, I think developing open source modem firmware is probably the least of your concerns.
I honestly wouldn't be surprised if the standard was written to make this kind of surveillance possible and that any modem refusing to cooperate would be spec incompliant. You can read most of the 3GPP spec for free on sites like https://portal.3gpp.org/ but I don't have the time or interest to dig through the unreadable stream of abbreviations and industry terms to find out.
It's all rather pointless anyway when 5G and to an extend 4G can geolocate you about as well as GPS can, barring reflections and such.