I’ve seen this a lot recently in manuscripts I edited and in television shows: When two people are talking on cell phones and one person disconnects, the other person is left with a dial tone. This does not happen in real life. If one person hangs up on a cell-to-cell call, the other person is simply left with dead air. But for some reason (perhaps to emphasize a dropped or suddenly disconnected call?), writers go out of their way to...