I use metal cookie tins with lids that seal tightly to store thumb drives and hdds of data, my most recent old phone, emergency crank-and-solar-powered radio, walkie talkies, etc.

I tested it by putting my phone in there, closing the lid, and then calling it. No ring. Then loosened the top and it rang. Tested it with streaming music too.

I tested with the radio too. It played music with top off, and went to static with top on.