IEEE Spectrum inducted it into its Consumer Electronics Hall of Fame. A specialist history site calls it the machine that made the category viable. Both are describing a device that reached the market forty-one years after someone else already held a granted patent for one.
The short version
- The PhoneMate 400 (1970 or 1971, founder Mark Brooks) is the machine most often credited today as the first commercially successful telephone answering machine, including by name in IEEE Spectrum’s Consumer Electronics Hall of Fame.
- Benjamin F. Thornton filed a patent for an automatic telephone message recorder on April 7, 1930, granted as U.S. 1,831,331 on November 10, 1931 — forty-one years before the PhoneMate 400, and five years earlier than the 1935 origin story most often repeated for this category.
- At least two companies made their own market before PhoneMate: the Electronic Secretary (1949, bought by General Telephone & Electronics in 1957) and the Ansafone (1960). Code-A-Phone’s maker filed a federal trademark for the name in 1961, a full decade before PhoneMate existed.
- The real hinge is not any one inventor. It is the FCC’s 1968 Carterfone ruling, which struck down the Bell System’s blanket ban on connecting non-Bell equipment to a phone line, and the 1975 order that named answering machines specifically.
- Date a used machine by its recording medium: reel-to-reel points to roughly 1949 through the late 1970s, cassette or microcassette to the late 1970s through the early 1990s, and no visible tape mechanism at all to a digital model from 1990 onward.
- Asking prices for a clean PhoneMate 400 or an early Code-A-Phone run from the single digits to about sixty dollars. No verified realized sale price could be found for either.
On this page
The machine everyone calls first
Mark Brooks founded PhoneMate in 1968 after leaving another electronics firm, and by 1970 or 1971 the company had a product on the market: the PhoneMate 400, a ten-pound box built, in Brooks’s own later description, “around a standard off-the-shelf box made of pressed sawdust covered with wood grain plastic,” running “a primitive Japanese reel-to-reel tape recorder” manufactured under contract by Asahi Corp. in Japan rather than anything built from solid-state electronics. It stored roughly twenty messages on small reels before a seller or owner had to rewind it by hand, and it sold for about $300.
That machine is the one IEEE Spectrum inducted into its Consumer Electronics Hall of Fame, and the one a specialist recording-history site calls “the viable answering machine you see today.” By 1982, PhoneMate was the largest supplier in a $140 million domestic answering-machine market, before Panasonic and Sony ate into its lead through the rest of the decade. Asahi acquired PhoneMate outright in 1989; Casio took a majority stake in Asahi two years later, which is the last stop in the corporate chain before the brand name ends up, decades later, attached to Casio’s own phone division.
“First” is doing a lot of work in that sentence, the same way it does across most of the categories this blog covers. The patent record for telephone message recording goes back considerably further than 1971, and PhoneMate was not even the first company to try to sell one.
The 1930 patent nobody cites
Benjamin F. Thornton filed a patent application on April 7, 1930, titled “Apparatus for Automatically Recording Telephonic Messages.” It was granted as U.S. Patent 1,831,331 on November 10, 1931. The mechanism it describes is a genuine answering machine: a motorized turntable holding recording discs, an electromagnetic switch that starts the motor when an incoming call connects the line, a stylus on a pivoting arm that cuts the message into the rotating disc, dual magazines that swap a blank disc in and a recorded one out after each call, a mechanical clock that stamps the time of receipt onto a paper strip, and a timed switch that shuts the motor off after a set recording window. It runs on ordinary AC or DC current with no battery. On paper, it is a complete answering machine, drawn and filed forty-one years before the PhoneMate 400 and five years before the date most general-audience histories give for the category’s invention.
That commonly repeated date is 1935, credited in several secondary sources to an inventor whose name is spelled two different ways depending on the source — Willy Muller in one, William Muller in another — described as a three-foot-tall device that reportedly found an early audience among Orthodox Jewish households who could not answer a telephone on the Sabbath. This research could not locate a patent number, a company name, or any primary citation behind that claim in either spelling. A separate, less-repeated claim credits a William Schergens with a phonographic-cylinder recording device as early as 1931, supposedly featured in the 1932 film Behind the Mask, also without a located patent or filing to confirm it.
Thornton’s patent is a granted, dated, numbered federal filing, readable in full on Google Patents. The 1935 and 1931 claims that get repeated far more often are not attached to any filing this research could find. That is not the same as saying they are false — only that they sit in a different evidentiary tier than a patent record does, and this guide treats them that way.
Why Bell Labs buried its own machine
Bell Laboratories researcher Clarence Hickman built a working tape-based answering machine by 1934, inside the same company that ran the entire U.S. telephone network. AT&T never brought it to market. The reason given across the sources covering this episode is business logic rather than technical failure: a machine that let a customer screen, defer, or avoid live calls altogether threatened the call volume the Bell System’s entire rate structure was built on. A device that made the telephone less urgent was not a device the phone company wanted its own customers using.
That decision fits a pattern this guide’s later sections return to directly. For most of the twentieth century, the Bell System did not just decline to sell answering machines — it worked to keep anyone else’s equipment off its network at all, under a tariff provision that banned any device “not furnished by the telephone company” outright. Hickman’s prototype sat unsold for the same underlying reason Electronic Secretary, Ansafone, and Code-A-Phone all had to build their early businesses around the edges of a network they were not allowed to plug directly into.
Who else already claimed first
Three companies had real, sellable products in the market before the PhoneMate 400 existed.
The Electronic Secretary reached the market in 1949, a business built by Joseph Zimmermann and George W. Danner as Electronic Secretary Industries in Wisconsin. It played an outgoing announcement off a 45 rpm record and recorded incoming messages to a wire recorder — a hybrid of two older recording technologies rather than one continuous tape. General Telephone & Electronics bought the company outright in 1957, the kind of acquisition that does not happen to a business without real revenue behind it. Zimmermann is credited in a secondary biography with a 1948 patent on the device, but this research could not independently locate that specific filing on Google Patents to confirm a number or an exact grant date, the same confidence gap that applies to the 1935 Muller claim above — the GTE acquisition, by contrast, is a separately documented business fact.
The Ansafone reached U.S. retail in 1960, designed by Dr. Kazuo Hashimoto and sold through a company called Phonetel. Multiple sources describe it as the first answering machine actually sold at U.S. retail under that specific framing — a narrower and more defensible claim than a flat “first ever.” Hashimoto reappears later in this category’s history: he patented a digital answering-machine architecture, U.S. 4,616,110, in 1983, putting his name on both sides of the analog-to-digital transition this guide’s dating section covers below.
Code-A-Phone, made by Ford Industries of Portland, Oregon, is usually dated to 1966 in general summaries of the category. Ford Industries’ own federal trademark filing for the name CODE-A-PHONE, however, is dated April 10, 1961 — a full five years earlier, and a decade before PhoneMate existed at all. That gap between the commonly cited product date and the company’s own trademark filing is covered fully in the records-disagree section below.
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The ruling that opened the jack
None of the companies above could originally connect their machines directly to a telephone line. Bell System tariff paragraphs 2.6.1 and 2.6.9 banned connecting any device “not furnished by the telephone company” to the network, no exceptions stated. Customers who wanted to use a non-Bell answering machine generally had to couple it to the handset acoustically — a microphone and speaker pressed against the receiver — rather than wiring it into the line directly.
The FCC struck that ban down on June 26, 1968, in the Carterfone decision (FCC 68-661, Docket Nos. 16942 and 17073), ruling the blanket prohibition “unreasonable, unlawful and unreasonably discriminatory.” The ruling did not ban phone companies from setting technical standards — it barred them from refusing a harmless customer-owned device outright. The FCC followed up with a 1975 Report and Order that named answering machines specifically, alongside toll restrictors and data modems, as devices entitled to direct interconnection, and the Part 68 equipment-registration program that formalized the standard began in 1977. A registration number on the back or bottom of a machine is a hard floor: that machine cannot predate 1977, no matter how old its styling looks.
Mark Brooks told IEEE Spectrum, years later, that PhoneMate’s own legal fight with AT&T over this exact kind of connection, built on the Carterfone precedent, helped establish rights that a decade further on let modems and computers connect to the phone network too. That account comes from Brooks himself in a retrospective interview, not from a court record this research could independently verify, and is presented here as his own telling of the company’s place in the story. What is independently confirmed is the ruling itself, three years before the PhoneMate 400 reached the market, and it is the actual reason a wave of answering-machine companies could finally sell a device that plugged straight into a phone jack instead of an acoustic coupler.
How to date a vintage machine
The recording medium is the fastest and most reliable dating tool, in three eras.
- Reel-to-reel, roughly 1949 through the late 1970s. Small open tape reels or a sealed reel cartridge, usually visible behind a lid or window. Cabinets from this era are heavy, finished in wood-grain plastic laminate over a pressed wood-composite shell — the same “furniture-style” treatment this blog’s guides to retro lighting and tension-pole lamps use as a dating marker for other small appliances of the period. The PhoneMate 400 and the earliest Code-A-Phone models sit in this window.
- Cassette or microcassette, roughly the late 1970s through the early 1990s. One or two visible cassette doors — some designs use a separate cassette for the outgoing announcement and another for incoming messages, later designs consolidate to one cassette or a single microcassette. The Smithsonian’s own Code-A-Phone holdings, a Model 5500 commercial unit from about 1981 and a Model 1100 from about 1982, both sit in this window.
- Digital, chip-based, 1990 onward. No visible tape mechanism of any kind. Kazuo Hashimoto patented the underlying digital architecture in 1983 (U.S. 4,616,110), but the first digital machine actually brought to market was AT&T’s Model 1337 in 1990, led by Trey Weaver — Hashimoto’s own infringement suit against it was dropped once the two designs proved architecturally different enough. A machine with no reel and no cassette door is 1990 or later, regardless of how dated the styling looks.
Check the back or underside for an FCC registration number, a small printed string usually beginning with a letter code. Its presence confirms a manufacture date of 1977 or later, the year the FCC’s Part 68 equipment-registration program took effect — a unit carrying one cannot be an original-run PhoneMate 400 or an original 1960s Ansafone, whatever a seller’s listing claims.
The look-alikes
| Object | How it differs |
|---|---|
| Dictaphone or dictation recorder | Records voice to a cylinder, belt, or cassette for later transcription. No phone-line jack, no ringer-activated switch, no handset cradle shaped to a telephone. |
| Home reel-to-reel tape recorder | Shares the wood-grain-plastic cabinet look of a 1950s-60s answering machine but has a microphone input rather than a modular telephone jack, and no call-activated switch. |
| Fax machine with a built-in answering machine | A real, later hybrid category. Adds a paper feed slot no stand-alone answering machine has, and post-dates the pure answering-machine category by a decade or more. |
| Cordless phone base with built-in answering machine | 1990s and later. The handset cradle is built into the same unit, unlike the stand-alone boxes meant to sit beside a separate phone. |
Where the records disagree
Code-A-Phone’s start date depends on which record is asked. General summaries of this category date the Code-A-Phone product to 1966. Ford Industries’ own federal trademark filing for CODE-A-PHONE, serial 72117589, is dated April 10, 1961, covering “automatic telephone answering devices.” Under the trademark law in force in 1961, before intent-to-use filings existed, a filing ordinarily followed actual use of the mark in commerce — which argues for the name already being in use by 1961, five years earlier than the date usually given. No catalog, advertisement, or shipping record from 1961 through 1965 could be located to confirm units were actually selling in that window rather than the mark simply being claimed early. Both dates are presented here; neither is resolved.
“First” means four different things across four different sources. Thornton’s 1930 filing is the first patent this research located on the public record. The Electronic Secretary’s 1949 launch is, per its own later marketing as reported secondhand, the first commercially successful model. The Ansafone’s 1960 debut is described as the first answering machine sold at U.S. retail under that specific framing. The PhoneMate 400’s 1971 debut is the frame IEEE Spectrum uses for its own Consumer Electronics Hall of Fame entry. Four claims, four different definitions of the word, not one fact four sources disagree about.
The 1935 and 1931 origin stories have no located primary citation. The Willy/William Muller device (1935) and the William Schergens device (1931, said to appear in the film Behind the Mask) both circulate in general-audience histories of this category. This research could not locate a patent number, company name, or other primary filing behind either claim, in contrast to Thornton’s dated, numbered, granted patent covered earlier in this guide.
What they sell for now
No verified realized sale price could be found for a PhoneMate 400 or an early Code-A-Phone unit in either direction. WorthPoint’s own listing for a boxed, unused PhoneMate 400-S sits behind its membership paywall with no price visible without an account, the same wall this blog has run into researching other categories. Every figure below is an asking price, not a confirmed sale, and is labeled that way.
- A factory-sealed, new-old-stock PhoneMate 400 asks $60.
- A used, boxed PhoneMate 400-S asks $6.
- An early Code-A-Phone Personal Answering System, Model 3000, asks $30; a Model 3300, described in its own listing as a “conversation recorder,” asks $26.99.
- Later 1980s-90s cassette-era models — a Code-A-Phone 5530 with its dual microcassettes, a PhoneMate 6000 boxed with its original manual — tend to ask closer to the low double digits than the low single digits. Completeness, the original box and paperwork, appears to move an asking price in this category more than age alone does, the opposite of what the Thornton-to-PhoneMate timeline above might suggest.
For another story where the brand name that won the market is not the name on the original patent, see this shop’s guide to the Motorola DynaTAC. For a different electronic device from the same general era whose trademark outlived the company that coined it, see the Speak & Spell guide. For a similar case where a remote’s brand name survives three owners and outlives every one of them, see the Zenith Space Command guide. See more Field Guides
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Sources
- U.S. Patent 1,831,331, Benjamin F. Thornton, “Apparatus for Automatically Recording Telephonic Messages,” filed April 7, 1930, granted November 10, 1931, for the 1930 patent record.
- The Consumer Electronics Hall of Fame: PhoneMate 400, IEEE Spectrum, for PhoneMate’s founding, the 400’s specifications and price, market-share figures, and Mark Brooks’s own account of the Carterfone-related legal fight.
- The History of the Telephone Answering Machine, Recording History, and A Business History of the Telephone Answering Machine, Recording History, for the Poulsen, Muller, Ansafone, and Electronic Secretary timeline entries.
- Answering machine, Wikipedia, for Clarence Hickman’s Bell Labs prototype, the William Schergens claim, Electronic Secretary’s GTE acquisition, and the digital-transition timeline including Hashimoto’s 1983 patent and AT&T’s Model 1337.
- In the Matter of Use of the Carterfone Device in Message Toll Telephone Service, 13 F.C.C.2d 420 (1968), for the Carterfone decision’s docket numbers, date, and holding.
- ACTA and Part 68: Past, Present, and Future, for the 1975 Report and Order naming answering machines specifically and the 1977 start of the Part 68 registration program.
- Ford Industries, Inc. Trademarks, Justia, for the CODE-A-PHONE trademark filing date, serial number 72117589.
- Telephone Answering Machine (Code-a-Phone Model 5500), Smithsonian National Museum of American History, and Telephone Answering Machine (Code-a-Phone Model 1100), Smithsonian National Museum of American History, for dated commercial-grade and consumer Code-A-Phone object records.
- Joseph Zimmermann (engineer), Wikipedia, for the Electronic Secretary inventor biography.
- Southwestern Bell – Answering Machine, Model FA935, Wikimedia Commons, for this guide’s photograph (image placed by this session unseen; framing and accuracy should be confirmed before any larger use).
- PicClick listings for PhoneMate 400, PhoneMate 400-S, Code-A-Phone Model 3000, and Code-A-Phone Model 3300, for this guide’s asking-price figures, each labeled as an asking price rather than a confirmed sale.
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