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
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
, 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
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.
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
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
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).