I’ve heard this repeated by others, including Rush Limbaugh, but cannot find a single technical source to prove it. If you know of a cell phone that can communicate with the cell system even when turned off, would you please pass the information along? Thanks.
In addition, phones in most American and Canadian states are designed to broadcast their position on the so-called E911 service for emergency use. The service uses signal triangulation as well as the phone's built-in GPS (if available), and is enabled by default for all new phones. In fact, the E911 service may track the phone even when it appears to be switched off. Although this is unlikely, there is nothing to stop the phone software simulating being powered down while in fact remaining on the network. To be sure your phone is actually offline, you need to removed the battery or use a signal-blocking bag - more on this later.
At this site: MobileActive.org
I can't verify the correctness of the information given.
One thing is certain, if your cell phone is on, it can be tracked. Any action you take to render the phone un-trackable (turn it off, remove the battery, throw the phone away) will result in making the phone dead weight. You may as well take the action that guarantees that it won't transmit.