This is a little extreme, but I've started turning off my phone or putting it in airplane mode when not expecting a call.
In addition to not being as distracted, I've had a marked decrease in spam calls - I think they tend to mark phones that repeatedly send them straight to VM as "cold".
It is known that complete operating systems run on every chip on that phone of which you don't have knowledge of or access to.
To think a software security solution provided by an OS, a pretty high-level abstraction when considering hardware, of the ability to turn off the radio is insane in these days and ages.
Furthermore with permanent batteries (or with a backup battery hidden inside) being off to the user doesn't mean anything either.
Assuming such an exploit exists, I don't think I'd be targeted with it. It's my understanding three letter agencies tend to hoard that sort of thing, not blast them at random privacy aficionados.
> the eavesdropping technique "functioned whether the phone was powered on or off."
https://www.cnet.com/news/fbi-taps-cell-phone-mic-as-eavesdr...
I would hope that the FBI would not override airplane mode on a smart phone... what if they did so while a suspect was actually on a plane?
A warrant doesn't give police the right to endanger others IIRC...
Nothing would happen. Just like nothing happens to the thousands of people who forget to switch their phones to airplane mode every day.
I would think a phone with a removable battery would otherwise serve your concerns.
The sentence was about permanent batteries with an aside about how technically a remove-able battery phone could still have power somewhere with it removed.