Re: is my phone ON or is it OFF?

On 25/04/2024 10:29, Nick Cine wrote:

On Thu, 25 Apr 2024 09:47:17 +0100, Jeff Layman wrote:
 

[*] or any other action such as lifting it up, or touching the screen,
or poking the fingerprint reader.

>
The lifting it up thing is interesting. I wonder if that's done with an
accelerometer? If so, it would be checking that too.

 A few more comments, but I don't know much about this topic.
 1. Even if a phone is "off", when you plug in a charger, "something
    happens", so is it really off? I don't know, but how does it charge?

The charging circuitry is within the battery itself. It controls the rate of charge and, in particular, monitors the temperature of the cell(s). If it gets too high it will stop the charging. Note though, that the connection from the phone's charger socket (lightning, USB, or whatever) goes through some of the phone's circuitry, so the phone knows the state of charge of its battery. That way its % charge can be displayed on the phone's screen, and battery-usage apps can let you know what's being used and how long the phone might last before recharging is essential.

2. The government has, in the past, secretly modified gangster's phones
    such that they looked to be off, but were secretly still transmitting.

What makes you think that was in the past and only affected crim's phones?! ;-)

3. The iPhone, I believe, is never off, which, I'm told, is how the FindMy
    sensing works for stolen phones.

I don't know about iPhones, but with my Xiaomi Android phone I can supposedly switch off "Find my phone". However, I'm not in control of the OS and really have little idea of what it does in the background. And even if you do work it all out, the next time an OS update appears you could be back at square one again!
You can only be sure that a phone is truly off by removing its battery, and that is becoming less likely every time a new model comes out. If you power down "completely" by, for example, giving a long press on the power switch, then you still have to accept the Manufacturer's word that the phone is "off" as there's no way of testing it AFAIAA.

How does any of that work? I don't know.

--
Jeff