Hollywood movies often show secret agents tossing cell phones out of car windows, and grabbing new ones to activate. In today’s world of almost universal surveillance and tracking, that is actually fairly good tradecraft. When operating in guerrilla warfare mode, a cell phone that is used more than a few times is a liability. So is a cell phone that is “turned off”, but that still has its battery installed. (They can still be tracked.)
In summary, here is some cellular phone tradecraft for times of genuinely deep drama:
1.) Don’t create a paper trail when buying clandestine phones. Pay cash for cell phones and don’t give your name. Preferably buy them in small stores without video surveillance.
2.) Activate phones only as needed.
3.) Never “recharge” the minutes on disposable cell phones. (This leaves a paper trail–at least leading to the place where you bought a recharge “minutes” card. And buying minutes via a phone call and credit card transaction leaves a huge paper trail.)
4.) Set a “phone talk time limit” for your group, depending on the then-current severity of the threat. Once you’ve reached the limit for each phone discard it. (But save the batteries, if they interchange.)
5.) Never program any cell phone numbers into your phone.