I just had an embarassing moment today. My phone went off, but I had forgotten to mute it. So, in the midst of a test, I had to turn it off, and apologize.
I'm death on cell phones. Kids at my school are always checking them under the desk. It's gotten so that I normally say, "turn it off" rather than confiscate it. It's just not worth the trouble to enforce the rules, if the admin isn't going to follow through.