What's the number-one rule when you go to a play or the symphony?
Turn off your cell phone!
Don't put it on vibrate - Just turn it off.
But, as CBS News correspondent Elaine Quijano reports, one patron forgot that simple rule this week during a concert by the New York Philharmonic - and it caused quite a stir.
"This ringtone," says conductor Alan Gilbert, "was going on and on and on; it was actually the loudest thing in the hall!"
Gilbert was in the midst of a performance of Mahler's Symphony No. 9 when the unthinkable happened: An iPhone began ringing.
And it didn't stop.
"There was so much tension," Gilbert says, "and such a stunned feeling, I think, for everybody in the room, but certainly for the musicians."
"Audience members started shaking their heads, sort of clucking, craning their necks to see who it is," said one concert-goer. "But it keeps going and going and going!"
To learn what happened next, click on the video above.