What demands an answer, but asks no question?

Why this works

This riddle plays with the concept of communication. A telephone is a device that "demands an answer" in the sense that when it rings, it indicates someone is trying to reach you, prompting you to pick it up. However, it does not ask a question on its own; rather, it facilitates a conversation where people can ask questions. The clever twist lies in the juxtaposition between the expectation of an answer and the absence of a literal question from the telephone itself.