The problem of the unanswered ring
A telephone is only useful if someone is there to answer it. For the first century of telephone service, an unanswered call simply vanished. Businesses used human answering services, in which an operator at a switchboard took messages for several subscribers, and households relied on neighbors or family. The idea of a machine that could answer for you and record what the caller said needed a way of storing sound, and that came from magnetic recording.
Magnetic recording and the telegraphone
The Danish engineer Valdemar Poulsen demonstrated a magnetic recorder in the late 1890s, which he called the telegraphone. It recorded sound as magnetized patterns on a steel wire, an early form of wire recording, and a patent was granted in 1898. Poulsen described telephone-related uses, including recording messages when no one was present, though his device was not a practical answering machine. The early recorders were expensive, the sound faint, and amplification weak.
The idea continued in other hands. Researchers at Bell Laboratories in the 1930s, including Clarence Hickman, built a machine that recorded messages on steel tape, and it is often mentioned as an early answering machine. Reports say that the company did not offer it commercially, partly from concern that customers would feel uneasy about recording telephone conversations, and partly because the technology was not yet ready. The story is mentioned in several histories, though the exact reasons are hard to confirm.
Tape comes of age
Magnetic recording took a large step forward after the Second World War, when German tape technology became widely known. Plastic tape coated with magnetic powder was cheaper, easier to handle and gave better sound than steel wire, which could snag and tangle. Tape recorders, including small portable recorders, spread through radio studios, offices and eventually homes. The combination of magnetic tape and electronics made answering devices feasible.
In the 1950s and 1960s, commercial answering machines were available, usually aimed at professionals such as doctors, salesmen and small business owners. They were bulky and costly. Telephone regulation in the United States also mattered: for many years telephone companies restricted attaching non-company equipment to their lines, and a 1968 decision involving a device called the Carterfone opened the way for customers to connect approved devices. Even so, details and timing varied by country.
The household machine
During the 1970s, smaller and cheaper machines reached the consumer market. A typical machine had two tapes or tape loops. One played a recorded greeting when the phone rang a set number of times, and the other recorded the caller’s message. Later models used standard cassettes or smaller microcassettes.
By the 1980s answering machines were a familiar household device in North America, Europe and Japan. They changed behavior: people learned to screen calls, to leave short messages, and to speak to a machine without feeling foolish. Some became known for creative or comic greetings. Remote retrieval, using a tone-sending device or a code from another telephone, allowed users to listen to their messages from afar.
Voicemail: the network takes over
A separate line of development placed message storage in the network rather than in a box at home. Computers could store speech digitally, and in the late 1970s the American engineer Gordon Matthews developed a voice message system for businesses, usually called VMX. It let employees send, store and forward spoken messages, and it was the direct ancestor of modern voicemail. Telephone companies and private systems adopted similar services during the 1980s.
For home users, the telephone company could offer a mailbox on its own equipment. Callers who reached no answer were routed into the mailbox, and subscribers retrieved messages by calling in. This removed the need for a machine in the house, had no tape to wear out, and could continue working during a power cut at the subscriber’s home.
From tape to chip
Even before network voicemail became common, home machines moved away from tape. Solid-state digital memory, a chip that stored the greeting and messages, appeared in the late 1980s and 1990s as memory became cheaper. Digital machines had no moving parts to jam, could skip quickly between messages, and could time-stamp each one.
Mobile phones accelerated the change. A mobile phone moves with its owner, so a separate box at a fixed address made less sense. Network voicemail was built into mobile service, and in 2007 smartphones introduced visual voicemail, which lists messages like email so that the user can choose which to play first. Some systems now offer text transcriptions, using speech technology similar to that in voice assistants, though accuracy varies.
What changed
Answering machines altered habits more than technology. A missed call turned from a lost opportunity into a message waiting. The machine’s role is also a small example of the way functions migrate: from a human service, to a box with tape, to a chip, to a network feature, and finally to an app. Few people today own a standalone answering machine, but the habit of leaving a message and the greeting that precedes it come directly from it.