[KarlInOhio]

I have been told that you can buy “antistat” bags like those used to protect PCBs from ESD damage and put your phone in it to prevent being “followed.”

Nope. I just tried it and it didn't work. The phone company still found me... well, my phone rang when I dialed it from a land line. At most it will weaken the signal so the phone will just turn up the power on its transmission to get through.

[NewHampshireDuo]

Antistat bags have a highly resistive coating that works as a static protection guard but it’s useless as a RF shield. You need metal or a dense metal mesh.