> I wondered how long it'd take for that to start happening. Will the
>> criminals catch on and start taking the batteries out of their phones?
> Can the FBI remotely power the phone even without the batteries being in?
Not without *some* kind of batteries. They might hide something inside so the externally visible battery could be removed, I suppose.
This reminds me of an old Sun Workstation eavesdropping trick, back when soundcards were new. Every Sun had a soundcard and a microphone. But every Sun ran multi-user UNIX. So you log on remotely, record a sound file, download it, and play it. (Or, if more clever, stream it to yourself in real time.) And so you hear whatever is going on in the room where the computer is.