The ring means somebody else is alive.
A man jumps from a high window. On the way down he hears a telephone ringing, and bitterly regrets jumping. Why?
Give me a hintThe hint
Ask who could have been calling him.
Reveal the answerHide the answer
He thought he was the last person alive on Earth
Source: Bruce J. Balfour, “Some Days Are Like That”, via Jed Hartman’s list of situation puzzles, no. 2.23