Why do cell phones work in elevators?

I’d have thought, the elevator car being a metal box, that it would shield the cell phone signal and render the phone inoperative; but the other day I saw someone chattering away on one in an elevator. Is the elevator car not as electromagnetically “tight” as I thought it was? Or was I dealing with a poseur?

An elevator isn’t designed to be an efficient Faraday cage by any stretch, so it’s bound to be leaky throughout a broad range of RF emissions. It doesn’t need to be RF shielded to function, so the engineers don’t bother. So, there are gaps all around the car that allow RF through. Certainly an elevator will attenuate the signal, sometimes strongly so, but in my experience most times you can get a useable signal

Can you ding hear ding me now ding?