Is there a way to boot to airplane mode on?

wombat9

I shutoff my phone periodically for days at a time, and when it turns back on it seems to always be on airplane mode off . I've learned to just remove the sim for periods but.... there has to be a setting I am missing.

Is removing the sim required every time?

I am thinking of using an rfid copper sheet.
Is that what most people use ?

Thanks

mar2112

Do you turn airplane mode on when you turn your phone off?

Tandara

First, airplane toggle should retain it's settings between restarts.
Second, unfortunately, on every reboot, right during booting, phone will enable radio for a short moment. That is AOSP problem and devs don't know how to solve it just yet.

de0u

Tandara Second, unfortunately, on every reboot, right during booting, phone will enable radio for a short moment.

I am aware of people expressing concerns that this might occur, but not evidence that it does occur. Are you in a position to share evidence that it does occur?

Skorp

Tandara

Afaik, that is known but nothing is transmitted. It is just a power spike as the battery supplies power to components, causing the radio to turn on. I don't think it means it connects to towers or anything like that.

de0u

Skorp Afaik, that is known but nothing is transmitted.

I am curious about how that is "known". Has it been measured?

Skorp

This is according to a GOS project member.

The device being delivered power will always have the radios make a spike of radio noise in a close proximity but it doesn't mean any identifiers are being transmitted out. You'll see the same with many other handheld devices including handheld radios.
That activity is simply just power being delivered to the components.

de0u

Skorp Booting a Pixel also delivers power to the DRAM, CPU, and GPU, all of which are likely to emit radio noise. Unless somebody is carefully measuring power delivery to the cellular modem in particular and/or radio emissions from the cellular modem in particular, attributing radio noise to a radio device may be unfounded. Is that what is being reported on?

Skorp

de0u
That is fair. It is possible it could be those other components.

Tandara

The thing is, baseband works independently from OS. I probably shouldn't have stated that it leaks 100%, but rather warning there is a possibility of it happening (by looking at other OEMs and knowing for sure that privacy wasn't a priority when Google was developing Pixels).

Moreover, how would removing SIM help in case your device has radio on? Even without a SIM, if what OP states is true, then phone would still broadcast its IMEI when A mode is off.
If you already tied SIM to that IMEI, then there would be no point in doing so (except preventing cellular data use in the background, which is also blocked cuz it's in BFU).

de0u

Tandara Many things are possible. I think part of the problem is that people are aware that part of the job of the cellular modem is registering with cell sites (true) and that registration involves communicating an IMEI (also true) and conclude that any time the cellular modem has power, even for a moment, naturally it is transmitting IMEIs on all frequencies.

When the baseband boots it doesn't even know what country it's in right now, thus which frequencies are legal to transmit on. Before registering with a cell site, it must find some, which it does by listening. That in turn requires powering on and conditioning an oscillator. These things take time.

If people have the idea that the first thing the baseband does when it gets power is to fire up the radio and shout out IMEIs frantically on all frequencies before the OS has a chance to power it down, I hope it would be possible to replace that idea with a desire to hire a qualified RF or cellular engineer to measure what actually happens for a specific device of interest.

DeletedUser495

Lots of words said here. How about turning the device into airplane mode, restarting and having a look at boot sequence log? Too technical for me, but perhaps there is one person on here who can wrap their head around it.