On: Why Snowden Asked Visitors in Hong Kong to Refrige...

[refurb]

Good question. The mesh size of the Faraday cage should be less than 1/2 the wave length of the RF radiation. At 2.4 GHz, the wavelength is ~125mm, and the mesh size of your typical microwave is a few mm. With the lower frequency of the cellular bands, you'd expect the microwave to work pretty well.

[marshray → refurb]

There's also the gap around the door, which is often poorly fitting on older worn-out units.

Still, the phone could be recording audio to upload at a later time. Audio storage capacity isn't likely to be a problem on modern phones.