An answering machine (other names are answerphone, ansaphone, ansafone and Telephone Answering Device (TAD)) is a machine. It is attached to a telephone line. If the phone is not answered after a few rings, it will play a message to the caller. The caller can then leave a message (after a sound that has become known as the beep). It is different form voicemail which is based in the network. Answering machines are installed at home (or at the office).
At first, answering machines used tapes (a smaller version of audio cassettes). Today, most systems use computer memory to store the messages and the prerecorded text. Many systems allow to listen to the left messages by simply calling the answering machine. Answering machines also have a system to save costs: If there are no new messages, there will be fewer rings.