Some "burner" phones never truly shut off. They reduce the rate at which they ping the cell phone towers in order to save battery life.
Put one inside a faraday cage with an RF monitor and watch how often that phone "lights up". It will be every 10-30 minutes when that phone is supposedly turned off.
Yes, that feature was designed into the phones at the requirement of various governments, so the phones could be tracked. The phone carriers are fully cooperative with such programs and will supply call logs and tracking logs on request to authorized government agencies.
Think of a cell phone as a government-sponsored personal tracking device with a 90-day memory and you have a reasonable assessment of what you are carrying.
The only way to be sure a phone is inactive is to pull the battery from the unit.
Note that many phones batteries are not user removable.
Buy a ton of cookies,eat the cookies or not,put the phone in the tin and put the lid on tight.
“The only way to be sure a phone is inactive is to pull the battery from the unit.”
Absolutely, 100%, true.
All modern phones have a “soft” power switch, which is constantly monitored by low level electronics. To see if you pushed it “ON.” So it’s an active circuit.
Without actually cutting batt power with a mechanical switch, it’s never completely off. But they are good about powering off all transmit and receive circuitry, so as long as they are a “trustworthy “ company, you’re ok.
Sopull the battery, or use a faraday cage (which do work great, and confuse everyone monitoring).
> The only way to be sure a phone is inactive is to pull the battery from the unit.
And hope that is the only battery on that device ;-)