On the sin of mobile or cell phones ringing in class, here’s a YouTube clip of Hugh Jackman stopping a performance because a phone is going off (and remains unanswered and unsilenced for quite a long time!):
As usual, the BBC has more detail. Of course, it’s not the first time that an actor has been annoyed by interrupting phones: like Jackman, but unlike David Suchet Richard Griffiths has stopped a play when a phone went off; but, unlike Jackman, he asked the offending audience member to leave. However, angry actors had better beware: don’t smash the phone or throw it at the offender!
Update: the original YouTube video to which I provided a link is down due to a copyright claim by TMZ, presumably relating to the clip to which this post is now linked.