> Email is very noisy and leaves tons of evidence all over the internet.
That’s correct, but email aren’t as linked to your real identity as how it’s the case with a phone number, knowing someone’s phone you can: deliver zero click zero day through an SMS, know their precise location, know their personal information as that number mostly used in government/banks/insurance/etc., plus real time data (listed below), so effectively knowing all that in a click on some aggregator (plantir?), the email isn’t as easy, while it’s not secure and never will be, it doesn’t provide that accurate information quickly about someone without extra steps, assuming it wasn’t a burner email anyway.
> The link you provided states the GNSS for the cell modem is GPS (or one of the other non-US systems). You said disabling GPS on the phone doesn't change this. Are you saying the modem has a second, secret GPS antenna? Or does it use some other global navigation system that isn't GPS?
I am aware what gnss is, and nope nope to both. Ok, let me explain, disabling the location services in your phone will not prevent your carrier from knowing your location, that will disable the OS/apps levels, but the gnss is embedded within your modem, with a firmware you don’t control or know. When you click the disable buttons you only prevent the OS of getting the location data, not the modem, and even if you happen (impossible) to open the hardware and cut the wires of the embedded gnss, the carrier can still estimate your location. Only when you stops the carrier connection is when you are truly not tracked, airplane mode is being the easiest but other means exist.
Per the link I shared before (also this if you need more details), 5G’s LTE Positioning Protocol LPP explicitly permits a network location server to ask a phone for GNSS measurements or a GNSS-derived location estimate.
https://www.etsi.org/deliver/etsi_ts/137300_137399/137355/16... (pages 214 to 230)
The modem firmware is proprietary and can’t prove it doesn’t share the location once you disable it, in fact, the reason why apple is disabling it in their own modems at hardware level proves it can’t be disabled on a software. Also, both android and apple say that basically just because you have location disabled doesn’t mean your location isn’t known for emergencies.
https://support.apple.com/en-us/102515
https://support.google.com/android/answer/9319337?hl=en
Even so, with location disabled, at hardware level, the carrier can still use: serving cell and sector to know your location, the timing of roundtrip RTT and time advance TA angle of arrival AoA and the usual suspect RSRP/RSRQ, signal strength and radio metrics, tower tilateration (canada admit using that for emergency https://crtc.gc.ca/eng/phone/911/can.htm), and positioning signals E-CID and OTDOA.
All of that won’t be an issue if you are not connected to the carrier, and to be connected you need a sim card, and that means you have a phone number, see how much you get exposed by only having a phone number, real time data or historical personal record? It’s why it’s still required in all services under the disguise of preventing spam or 2FA. Bottom line: don’t trust a service that requires a phone number, try to always have your phone disconnected from carrier by at least airplane mode, or better measures.