Regarding the Faraday bag, as I mentioned in another comment, that is not useful because the phone could be recording your audio anyway and then just transmit it later when you take it out of the bag. What you'd really want is some kind of soundproof box, but I'm not sure if an effective one exists because microphones can be sensitive and audio recordings can be amplified.

IIRC, Snowden tried to use a hotel room minifridge for this purpose.

Faraday bags are not effective against all frequencies. Specifically the 5G frequencies are known to be very difficult to block with a cage ( but do have relatively short ranges)

It also is ineffective at blocking audio which can be shipped out as soon as it comes out of the bag.

> It also is ineffective at blocking audio

If you turn your phone off and immediately put it in a Faraday bag, how would it receive a remote command to turn on and start recording audio?

That's implying that it is actually off and not just pretending to be off, and that it requires a command to start recording instead of just constantly recording and only uploading when commanded to

If we're assuming a well-funded and motivated attacker, surely any device is fair game for being modified to record you even when it's apparently off?

Of course this applies whether it appears to have a removable "battery" or not.

Far enough down the threat model rabbit hole the real solution is just ditch the phone if you're doing anything mildly antigovernment. That at least forces them to do a bit more work to spy on you.

That's always one of the big issues in opsec/security discussions, we can always imagine a more motivated or well funded attacker but the likelihood of those being deployed against you change with the difficulty of implementing those methods.

Would putting it inside a microwave work? I think I recall Snowden did that but I'm not entirely sure I remember correctly.

Edit: on the other hand, I'm now considering the possibility that the phone might be recording your audio even without network access and then transmit it later when you take it outside the microwave. So you'd have to be physically far away from the microwave for the microphone not to hear you, which means the microwave and faraday cages don't add anything useful.

As long as you turn the microwave on, yes that will be effective.

Running or not? /s The former is a definite yes but expensive while the latter is probably also fine for many situations.

I prefer hardware kill switches (and my phone has them).

Which phone is that?

Librem 5.