From https://grapheneos.org/faq: "Connecting to your carrier's network inherently depends on you identifying yourself to it and anyone able to obtain administrative access. Activating airplane mode will fully disable the cellular radio transmit and receive capabilities, which will prevent your phone from being reached from the cellular network and stop your carrier (and anyone impersonating them to you) from tracking the device via the cellular radio. The baseband implements other functionality such as Wi-Fi and GPS functionality, but each of these components is separately sandboxed on the baseband and independent of each other. Enabling airplane mode disables the cellular radio, but Wi-Fi can be re-enabled and used without activating the cellular radio again. This allows using the device as a Wi-Fi only device."

When I am at home, I am WIFI only. When I am out, WIFI & bluetooth are off. This takes some discipline at first but then just becomes habit. I know the spot on my commute home where I switch my settings.

I can promise that airplane mode does not fully disable the cellular radio, at least not on Samsung phones. Repeating a comment above: I can verify they do in fact receive data - I worked an immersive art project that had 100 Samsung cell phones that were in airplane mode, and we found out the hard and noisy way that they were still able to receive emergency and AMBER alerts (U.S. alerts that notify of potential child abductions).

BTW habitually switching at the same time and place is terrible opsec. It leaks a ton of information.

Yeah I'm not sure what information this really protects assuming you're only communicating over encrypted channels (https) already.

In theory it could protect location data from the carrier for locating you with a wild amount of opsec practice but I highly doubt you could pull that off for a daily driver.

Having wifi/bluetooth off in public isn't a terrible idea though as those are generally much easier attack surfaces and are leakier.

It is the same general location about half a mile from home where I flip over. This is to ensure location from cell tower triangulation does not identify my home and therefore me.

It’s all about your threat model.

Suppose you wanted to find someone that aways turned on their phone on at ~8:15 AM and found someone that always turned their phone off at ~8:10 AM within 15 miles. How difficult would you say it was to make this connection?

Nobody is looking for me. I don't have any regular commute either. I just make sure not to use cellular at my house since that would narrow the owner of the SIM down to one of the people living in this house.

Do you own a car with OnStar or SeriusXm ?

I have O*. How do I disable it?

No. I ride a bike.

The baseband is an entirely separate SoC that is a blackbox outside of the control of GrapheneOS. And your radios are solely under the control of that system. GrapheneOS just asks it nicely to do things on its behalf.

All of these privacy focussed phone OSes tread lightly on the fact that there are a grand total of zero modern open source basebands in existence.

Agreed. We can only mitigate by tactics: -not associating the device ID's to personal ID's. -only using cellular in limited situations. -rotating the SIMs periodically with other family members

You don’t get to choose those things if you don’t choose what the radio does. Swapping SIMs around doesn’t accomplish that. The hardware and software that the baseband has entirely within the confines of its own black box is enough to track you.

I would never trust that. It is how thing are supposed to work, not the way they necessarily will. Just buy a phone with physical disconnect switches if it is important enough for you.

I appreciate the extra information. I'm still skeptical on any phone except the OS/HW combo the faq was written against (which by the way was not in your original post)

In my country, this one girl is buying prepaid SIMs and selling them on darknet. Which is fully legal. Still she got notified from our intelligence agency, lol. They're butt-hurt a lot from this.