I'm an electronics engineer, and I have a spectrum analyzer (measures transmit power, even short pulses). By making a call, I established the frequency range and power that it operated on. I also established a controlled radio environment where no signals except the cell phone's would register on the analyzer. Then, I turned off the cell phone and continued monitoring it.
No transmission for a half hour now.
As soon as I turned it back on, it started transmitting again.
They can't track ya if ya don't transmit.
Or if they can't hear ya -- y'all with the Faraday Cage ideas are on the right track. Just wrap it in good ol' aluminum foil.
By "controlled environment" - would your phone have been able to receive a ping from the tower? Closely reading the statement in the book, it (sort of) implies that the phone may have to be commanded to transmit when switched off.
Well, when in doubt -— I sent an email to the book’s author.
I did get a reply from the book’s author. “Manipulated” means that software has to be installed to make the phone beacon when switched off. This is intrusive and requires a wiretap warrant to be legal.