Was watching the news about those package bombs, and realized how easy it was in this day and age to make a bomb that can be set off at command from almost anywhere, using a simple cell phone. You don't even need to be a techie - any thug could set it up who knew something about detonators.

No microcircuits, no weird circuit mods. The fundamental gimmick is the cell phone vibrator motor, which, when you open a cell phone, sits right there with one red wire and one blue one sticking out of it. Pretty obvious.

Anything programmed into the cell phone to create a "ring" can be set to pipe some voltage through those two wires. Hook them to whatever nasty device you like, mail it somewhere, then use the calendar function, alarm clock function, or just call the damn phone from somewhere within visual range or even some other part of the planet. Cripes, I've got a website that will tell you where a given plane is flying at any point in its flight.

Fixes for this might include devices that detect an active cell phone (which, I believe, sends out a frequent "interrogation" signal to check for towers or something). Faraday shielding in secure areas wouldn't hurt, and I'd probably do that anyway for sensitive installations. Would it be hard to shield the cargo compartment of an aluminum airplane? Maybe not.