Comment by ssl-3

Way back in the flip phone days, I had evil tracking software on my corpo phone for a time.

I didn't mind that they knew where I was when I was being paid, but I had issues with abuse by one particular manager (who was more my equal than my boss, but nevermind that).

This tracking software could be disabled with a couple of button pushes, or the phone simply turned off, but these action generated alerts that were sent home to the mothership. I did not like this aspect at all.

So I bought a little Faraday bag from somewhere in China -- back then, probably from DealExtreme. It fit the phone so well that it seemed like it must have been made for that specific model (even though it almost certainly was not). Inside, it had two compartments: One that encapsulated the device well-enough with conductive fabric, and another that was outside of (and adjacent to) that envelope, which just protected the phone from things like incidental abrasions.

I used it as an every-day phone case. When I wanted the phone to work, I used the non-shielded part. If I wanted the phone to not work, then I used the shielded compartment instead.

In imprecise practical terms, this bag blocked successful RF communications. (And I knew this to be true, because I also had access to the mothership's web interface and could review the tracking data for myself and my coworkers.)

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I can accept that "blocked" is not the most-precise term. In a way that is similar to many other things, a valid and accurate technical description of what was achieved would require additional precision.

But such precision is not always necessary in order to succinctly have words convey their desired intent, and I don't think it's required here for OP's intent to be understood.