An answering machine, also known as an answerphone (especially in the UK and some Commonwealth countries), and sometimes/formerly ansaphone or ansafone or telephone answering device (TAD), is a device invented in 1935, by Benjamin Thornton, and independently in Switzerland by Willy Mueller. Thornton's device would be attached to a telephone and could be set to record a voice message from a caller. By utilizing a clock attachment, the machine could also forward the messages as well as keep track of the time they were made. Unlike voicemail, which can be a centralized or networked system that performs a similar function, an answering machine must be installed in the customer's premises alongside — or incorporated within — the customer's telephone.

While early answering machines used magnetic tape technology, most modern equipment uses solid state memory storage; some devices use a combination of both, with a solid state circuit for the outgoing message and a cassette for the incoming messages. In 1983 Kazuo Hashimoto received a patent for a Digital Answering Machine architecture with US Patent 4,616,110. The first Digital Answering Machine brought to the market was AT&T's 1337; an activity led by Trey Weaver. Mr. Hashimoto sued AT&T but quickly dropped the suit because the AT&T architecture was significantly different than his patent.

Operation

On a two-cassette answerphone, there is an outgoing cassette, usually a special endless loop tape, which plays a pre-recorded message down the line to the caller who rang the number after a certain number of rings. Once the message is complete, the outgoing cassette stops and the incoming cassette starts recording the caller's message, and then stops once the line is cut.

Single-cassette answering machines first play the announcement, then fast-forward to the next available space for recording, then record the caller's message. If there are many previous messages, fast-forwarding through them can cause a perceptible delay.

An answerphone may have a remote listening facility whereby the answerphone owner can ring their home number and, by either sending a tone down the line using a special device, or by entering a code on the remote telephone's keypad, can listen to messages when away from home.

Most modern answering machines have a system for greeting. The owner may record his or her message that will be played back to the caller, or an automatic message will be played if the owner does not record one. Answering machines can usually be programmed to take the call at a certain number of rings. This is useful if the owner is screening calls and does not wish to speak with all callers.

Many devices offer a "toll saver" function, whereby the machine answers only after several rings (typically four) if no messages have been left, but answers after a smaller number of rings (usually two) if there are messages. This allows the owner to know whether there are messages waiting; if there are none, he or she can hang up the phone on the third ring without incurring a call charge.

Some machines also allow themselves to be activated, if they have been switched off, by calling and allowing the phone to ring a certain large number of times (usually 10-15).

See also

• Voicemail

References

1. About.com: http://www.blackinventor.com/pages/benjaminthornton.html