>>>> audio capture the best idea.  non-serial tower associations are an
>>>> anomaly alerted and acted upon.)

>Faraday cages concept really depend on the freqs they are designed
>>to inhibit, pressure, sound, radio, optic, etc. Given wide enough freqs,
>one cage does not service all.
>A fridge has plastec and magnetic gaskets, over maybe 2cm variant
>gap, so not a complete EM seal (at whichever specifical freqs).
>And grounding issue. But good at human sound deading.
>Microwave door shield is closer to cell phone freq shield.
>If you cannot simply remove the battery preferably, that is.
>As always, test first. And is easy to find phones to test
>all phone bands with.
>TEMPEST.

Why not wrap the phone in a couple of layers of aluminum foil?  (Although, it won't shield against audio if that's being recorded even while an RF contact does not exist...)

     Jim Bell