“And if you really DO need to take a cell phone with you, try to keep it in a Faraday cage if you aren’t actively using it”
Turning it off would work, wouldn’t it? Maybe not???
Nope. Many apps, the phone company and the government can turn it on if they want even after you turn it off; Some phones are NEVER actually off even if you pull the battery, Faraday cage is the only way to be sure.