History of the telephone

This history of the telephone chronicles the development of the electrical telephone, and includes a brief review of its predecessors.

Actor portraying Alexander Graham Bell in an AT&T promotional film (1926)
Actor portraying Alexander Graham Bell in a 1915 silent film. Shows Bell's first telephone transmitter (microphone), invented 1876 and first displayed at the Centennial Exposition, Philadelphia.

Telephone prehistory

Mechanical devices

A 19th century acoustic tin can or "lovers' telephone"

Before the invention of electromagnetic telephones, mechanical acoustic devices existed for transmitting speech and music over a distance greater than that of normal direct speech. The earliest mechanical telephones were based on sound transmission through pipes or other physical media.[1] The acoustic tin can telephone, or "lovers' phone", has been known for centuries. It connects two diaphragms with a taut string or wire, which transmits sound by mechanical vibrations from one to the other along the wire (and not by a modulated electric current). The classic example is the children's toy made by connecting the bottoms of two paper cups, metal cans, or plastic bottles with tautly held string.[1][2]

Among the earliest known experiments were those conducted by the British physicist and polymath Robert Hooke from 1664 to 1685.[1][3] An acoustic string phone made in 1667 is attributed to him.[4]

For a few years in the late 1800s, acoustic telephones were marketed commercially as a niche competitor to the electrical telephone. When the Bell telephone patents expired and many new telephone manufacturers began competing, acoustic telephone makers quickly went out of business. Their maximum range was very limited.[2] An example of one such company was the Pulsion Telephone Supply Company created by Lemuel Mellett in Massachusetts, which designed its version in 1888 and deployed it on railroad right-of-ways.

Additionally, speaking tubes have long been common, especially within buildings and aboard ships, and are still in use today. [5]

Electrical devices

The telephone emerged from the making and successive improvements of the electrical telegraph. In 1804, Spanish polymath and scientist Francisco Salva Campillo constructed an electrochemical telegraph.[6] The first working telegraph was built by the English inventor Francis Ronalds in 1816 and used static electricity.[7] An electromagnetic telegraph was created by Baron Schilling in 1832. Carl Friedrich Gauss and Wilhelm Weber built another electromagnetic telegraph in 1833 in Göttingen.

Telephone Centennial Issue 1976-13c
Bell prototype telephone stamp
Centennial Issue of 1976

The electrical telegraph was first commercialised by Sir William Fothergill Cooke and entered use on the Great Western Railway in England. It ran for 13 mi (21 km) from Paddington station to West Drayton and came into operation on April 9, 1839.

Another electrical telegraph was independently developed and patented in the United States in 1837 by Samuel Morse. His assistant, Alfred Vail, developed the Morse code signaling alphabet with Morse. America's first telegram was sent by Morse on January 6, 1838, across 2 miles (3 km) of wiring.

Invention of the telephone

Credit for the invention of the electric telephone is frequently disputed, and new controversies over the issue have arisen from time to time. Charles Bourseul, Innocenzo Manzetti, Antonio Meucci, Johann Philipp Reis, Alexander Graham Bell, and Elisha Gray, amongst others, have all been credited with the telephone's invention. The early history of the telephone became and still remains a confusing morass of claims and counterclaims, which were not clarified by the huge mass of lawsuits to resolve the patent claims of many individuals and commercial competitors. The Bell and Edison patents, however, were commercially decisive, because they dominated telephone technology and were upheld by court decisions in the United States.

Antonio Meucci

Antonio Meucci, 1854, constructed telephone-like devices.


Johann Philipp Reis, 1860, constructed prototype 'make-and-break' telephones, today called Reis telephone.

Alexander Graham Bell

Alexander Graham Bell was awarded the first U.S. patent for the invention of the telephone in 1876.

Portrait elisha gray

Elisha Gray, 1876, designed a telephone using a water microphone in Highland Park, Illinois.

Thomas Edison, 1878

Thomas Edison invented the carbon microphone which produced a strong telephone signal.

The modern telephone is the result of work of many people.[8] Alexander Graham Bell was, however, the first to patent the telephone, as an "apparatus for transmitting vocal or other sounds telegraphically". Bell has most often been credited as the inventor of the first practical telephone. However, in Germany Johann Philipp Reis is seen as a leading telephone pioneer who stopped only just short of a successful device, and as well the Italian-American inventor and businessman Antonio Meucci has been recognized by the U.S. House of Representatives for his contributory work on the telephone.[9] Several other controversies also surround the question of priority of invention for the telephone.

The Elisha Gray and Alexander Bell telephone controversy considers the question of whether Bell and Gray invented the telephone independently and, if not, whether Bell stole the invention from Gray. This controversy is narrower than the broader question of who deserves credit for inventing the telephone, for which there are several claimants.

The Canadian Parliamentary Motion on Alexander Graham Bell article reviews the controversial June 2002 United States House of Representatives resolution recognizing Meucci's contributions 'in' the invention of the telephone (not 'for' the invention of the telephone). The same resolution was not passed in the U.S. Senate, thus labeling the House resolution as "political rhetoric". A subsequent counter-motion was unanimously passed in Canada's Parliament 10 days later which declared Bell its inventor. This webpage examines critical aspects of both the parliamentary motion and the congressional resolution.

Telephone exchange

The main users of the electrical telegraph were post offices, railway stations, the more important governmental centers (ministries), stock exchanges, very few nationally distributed newspapers, the largest internationally important corporations, and wealthy individuals.[10] Telegraph exchanges worked mainly on a store and forward basis. Although telephones devices were in use before the invention of the telephone exchange, their success and economical operation would have been impossible with the schema and structure of the contemporary telegraph systems.

Prior to the invention of the telephone switchboard, pairs of telephones were connected directly with each other, which was primarily useful for connecting a home to the owner's business (They practically functioned as a primitive intercom).[11] A telephone exchange provides telephone service for a small area. Either manually by operators, or automatically by machine switching equipment, it interconnects individual subscriber lines for calls made between them. This made it possible for subscribers to call each other at homes, businesses, or public spaces. These made telephony an available and comfortable communication tool for many purposes, and it gave the impetus for the creation of a new industrial sector.

The telephone exchange was an idea of the Hungarian engineer Tivadar Puskás (1844 - 1893) in 1876, while he was working for Thomas Edison on a telegraph exchange.[12][13][14][15][16] The first commercial telephone exchange was opened at New Haven, Connecticut, with 21 subscribers on 28 January 1878,[17] in a storefront of the Boardman Building in New Haven, Connecticut. George W. Coy designed and built the world's first switchboard for commercial use. Coy was inspired by Alexander Graham Bell's lecture at the Skiff Opera House in New Haven on 27 April 1877.[17]

In Bell's lecture, during which a three-way telephone connection with Hartford and Middletown, Connecticut, was demonstrated, he first discussed the idea of a telephone exchange for the conduct of business and trade. On 3 November 1877, Coy applied for and received a franchise from the Bell Telephone Company for New Haven and Middlesex Counties. Coy, along with Herrick P. Frost and Walter Lewis, who provided the capital, established the District Telephone Company of New Haven on 15 January 1878.[17]

The switchboard built by Coy was, according to one source, constructed of "carriage bolts, handles from teapot lids and bustle wire." According to the company records, all the furnishings of the office, including the switchboard, were worth less than forty dollars. While the switchboard could connect as many as sixty-four customers, only two conversations could be handled simultaneously and six connections had to be made for each call.[17]

The District Telephone Company of New Haven went into operation with only twenty-one subscribers, who paid $1.50 per month. By 21 February 1878, however, when the first telephone directory was published by the company, fifty subscribers were listed. Most of these were businesses and listings such as physicians, the police, and the post office; only eleven residences were listed, four of which were for persons associated with the company.[17]

The New Haven District Telephone Company grew quickly and was reorganized several times in its first years. By 1880, the company had the right from the Bell Telephone Company to service all of Connecticut and western Massachusetts. As it expanded, the company was first renamed Connecticut Telephone, and then Southern New England Telephone in 1882.[17] The site of the first telephone exchange was granted a designation as a National Historic Landmark on 23 April 1965. However it was withdrawn in 1973 in order to demolish the building and construct a parking garage.[17]

Early telephone developments

The following is a brief summary of the history of the development of the telephone:

Telefono di Meucci - Museo scienza tecnologia Milano 02148-02147 dia
Antonio Meucci's telephone.
A French Gower telephone of 1912 at the Musée des Arts et Métiers in Paris
  • 1667: Robert Hooke invented a string telephone that conveyed sounds over an extended wire by mechanical vibrations. It was to be termed an 'acoustic' or 'mechanical' (non-electrical) telephone.
  • 1753: Charles Morrison proposes the idea that electricity can be used to transmit messages, by using different wires for each letter.[18]
  • 1844: Innocenzo Manzetti first mooted the idea of a "speaking telegraph" (telephone).
  • 1854: Charles Bourseul writes a memorandum on the principles of the telephone. (See the article: "Transmission électrique de la parole", L'Illustration, Paris, 26 August 1854.)
  • 1854: Antonio Meucci demonstrates an electric voice-operated device in New York; it is not clear what kind of device he demonstrated.
  • 1861: Philipp Reis constructs the first speech-transmitting telephone
  • 28 December 1871: Antonio Meucci files a patent caveat (No. 3353, a notice of intent to invent, but not a formal patent application) at the U.S. Patent Office for a device he named "Sound Telegraph".[19]
  • 1872: Elisha Gray establishes Western Electric Manufacturing Company.
  • 1 July 1875: Bell uses a bi-directional "gallows" telephone that was able to transmit "voicelike sounds", but not clear speech. Both the transmitter and the receiver were identical membrane electromagnet instruments.
  • 1875: Thomas Edison experiments with acoustic telegraphy and in November builds an electro-dynamic receiver, but does not exploit it.
  • 1875: Hungarian Tivadar Puskas (the inventor of telephone exchange) arrived in the USA.
  • 6 April 1875: Bell's U.S. Patent 161,739 "Transmitters and Receivers for Electric Telegraphs" is granted. This uses multiple vibrating steel reeds in make-break circuits, and the concept of multiplexed frequencies.
  • 20 January 1876: Bell signs and notarizes his patent application for the telephone.
  • 11 February 1876: Elisha Gray designs a liquid transmitter for use with a telephone, but does not build one.
  • 7 March 1876: Bell's U.S. patent No. 174,465 for the telephone is granted.
  • 10 March 1876: Bell transmits the sentence: "Mr. Watson, come here! I want to see you!" using a liquid transmitter and an electromagnetic receiver.
  • 30 January 1877: Bell's U.S. patent No. 186,787 is granted for an electromagnetic telephone using permanent magnets, iron diaphragms, and a call bell.
  • 27 April 1877: Edison files for a patent on a carbon (graphite) transmitter. Patent No. 474,230 was granted on 3 May 1892, after a 15-year delay because of litigation. Edison was granted patent No. 222,390 for a carbon granules transmitter in 1879.
  • 6 October 1877: the Scientific American publishes the invention from Bell - at that time still without a ringer.
  • 25 October 1877: the article in the Scientific American is discussed at the Telegraphenamt in Berlin
  • 12 November 1877: The first commercial telephone company enters telephone business in Friedrichsberg close to Berlin[20] using the Siemens pipe as ringer and telephone devices built by Siemens.
  • 1877: The first experimental Telephone Exchange in Boston.
  • 1877: First long-distance telephone line
  • 1877:Emile Berliner invented the telephone transmitter.
  • 28 January 1878: The first commercial US telephone exchange opened in New Haven, Connecticut.
  • 15 June 1878: The first commercial toll line enters operation, connecting Springfield and Holyoke, Massachusetts[21]
  • 1887: Tivadar Puskás introduced the multiplex switchboard.
  • 1915: First U.S. coast-to-coast long-distance telephone call, ceremonially inaugurated by A.G. Bell in New York City and his former assistant Thomas Augustus Watson in San Francisco, California.

Early commercial instruments

Magneto wall telephone 1917 open
1917 wall telephone, open to show magneto and local battery

Early telephones were technically diverse. Some used liquid transmitters which soon went out of use. Some were dynamic: their diaphragms vibrated a coil of wire in the field of a permanent magnet or vice versa. Such sound-powered telephones survived in small numbers through the 20th century in military and maritime applications where the ability to create its own electrical power was crucial. Most, however, used Edison/Berliner carbon transmitters, which were much louder than the other kinds, even though they required induction coils, actually acting as impedance matching transformers to make it compatible to the line impedance. The Edison patents kept the Bell monopoly viable into the 20th century, by which time telephone networks were more important than the instrument.

Early telephones were locally powered, using a dynamic transmitter or else powering the transmitter with a local battery. One of the jobs of outside plant personnel was to visit each telephone periodically to inspect the battery. During the 20th century, "common battery" operation came to dominate, powered by "talk battery" from the telephone exchange over the same wires that carried the voice signals. Late in the century, wireless handsets brought a revival of local battery power.

The earliest telephones had only one wire for both transmitting and receiving of audio, and used a ground return path, as was found in telegraph systems. The earliest dynamic telephones also had only one opening for sound, and the user alternately listened and spoke (rather, shouted) into the same hole. Sometimes the instruments were operated in pairs at each end, making conversation more convenient but also more expensive.

1st Telephone Central Office
Historical marker commemorating the first telephone central office in New York State (1878)

At first, the benefits of a switchboard exchange were not exploited. Instead, telephones were leased in pairs to the subscriber, for example one for his home and one for his shop, and the subscriber had to arrange with telegraph contractors to construct a line between them. Users who wanted the ability to speak to three or four different shops, suppliers etc. would obtain and set up three or four pairs of telephones. Western Union, already using telegraph exchanges, quickly extended the principle to its telephones in New York City and San Francisco, and Bell was not slow in appreciating the potential.

Signaling began in an appropriately primitive manner. The user alerted the other end, or the exchange operator, by whistling into the transmitter. Exchange operation soon resulted in telephones being equipped with a bell, first operated over a second wire and later with the same wire using a condenser. Telephones connected to the earliest Strowger automatic exchanges had seven wires, one for the knife switch, one for each telegraph key, one for the bell, one for the push button and two for speaking.

Rural and other telephones that were not on a common battery exchange had hand cranked "magneto" generators to produce an alternating current to ring the bells of other telephones on the line and to alert the exchange operator.

In 1877 and 1878, Edison invented and developed the carbon microphone used in all telephones along with the Bell receiver until the 1980s. After protracted patent litigation, a federal court ruled in 1892 that Edison and not Emile Berliner was the inventor of the carbon microphone. The carbon microphone was also used in radio broadcasting and public address work through the 1920s.

1896 telephone
1896 Telephone (Sweden)

In the 1890s a new smaller style of telephone was introduced, the candlestick telephone, packaged in three parts. The transmitter stood on a stand, known as a "candlestick" for its shape, hence the name. When not in use, the receiver hung on a hook with a switch in it, known as a "switchhook." Previous telephones required the user to operate a separate switch to connect either the voice or the bell. With the new kind, the user was less likely to leave the phone "off the hook". In phones connected to magneto exchanges, the bell, induction coil, battery, and magneto were in a separate bell box called a "ringer box." In phones connected to common battery exchanges, the ringer box was installed under a desk, or other out of the way place, since it did not need a battery or magneto.

Cradle designs were also used at this time, having a handle with the receiver and transmitter attached, separate from the cradle base that housed the magneto crank and other parts. They were larger than the "candlestick" and more popular.

Disadvantages of single wire operation such as crosstalk and hum from nearby AC power wires had already led to the use of twisted pairs and, for long distance telephones, four-wire circuits. Users at the beginning of the 20th century did not place long distance calls from their own telephones but made an appointment to use a special sound proofed long distance telephone booth furnished with the latest technology.

Around 1893, the country leading the world in telephones per 100 persons (teledensity) was Sweden with 0.55 in the whole country but 4 in Stockholm (10,000 out of a total of 27,658 subscribers).[22] This compares with 0.4 in USA for that year.[23] Telephone service in Sweden developed through a variety of institutional forms: the International Bell Telephone Company (a U.S. multinational), town and village co-operatives, the General Telephone Company of Stockholm (a Swedish private company), and the Swedish Telegraph Department (part of the Swedish government). Since Stockholm consists of islands, telephone service offered relatively large advantages, but had to use submarine cables extensively. Competition between Bell Telephone and General Telephone, and later between General Telephone and the Swedish Telegraph Dept., was intense.

In 1893, the U.S. was considerably behind Sweden, New Zealand, Switzerland, and Norway in teledensity. The U.S. became the world leadership in teledensity with the rise of many independent telephone companies after the Bell patents expired in 1893 and 1894.

20th century developments

Old Receiver schematic, c.1906
A German rotary dial telephone, the W48
Transmitting tower top us
Top of cellular telephone tower

By 1904 over three million phones in the U.S.[24] were connected by manual switchboard exchanges. By 1914, the U.S. was the world leader in telephone density and had more than twice the teledensity of Sweden, New Zealand, Switzerland, and Norway. The relatively good performance of the U.S. occurred despite competing telephone networks not interconnecting.[25]

What turned out to be the most popular and longest lasting physical style of telephone was introduced in the early 20th century, including Bell's model 102 telephone. A carbon granule transmitter and electromagnetic receiver were united in a single molded plastic handle, which when not in use were placed in a cradle in the base unit. The circuit diagram[26] of the model 102 shows the direct connection of the receiver to the line, while the transmitter was induction coupled, with energy supplied by a local battery. The coupling transformer, battery, and ringer were in a separate enclosure from the desk set. The rotary dial in the base interrupted the line current by repeatedly but very briefly disconnecting the line 1 to 10 times for each digit, and the hook switch (in the center of the circuit diagram) permanently disconnected the line and the transmitter battery while the handset was on the cradle.

Starting in the 1930s, the base of the telephone also enclosed its bell and induction coil, obviating the need for a separate ringer box. Power was supplied to each subscriber line by central office batteries instead of the user's local battery which required periodic service. For the next half century, the network behind the telephone grew progressively larger and much more efficient, and after the rotary dial was added the instrument itself changed little until Touch-Tone signaling started replacing the rotary dial in the 1960s.

The history of mobile phones can be traced back to two-way radios permanently installed in vehicles such as taxicabs, police cruisers, railroad trains, and the like. Later versions such as the so-called transportables or "bag phones" were equipped with a cigarette lighter plug so that they could also be carried, and thus could be used as either mobile two-way radios or as portable phones by being patched into the telephone network.

In December 1947, Bell Labs engineers Douglas H. Ring and W. Rae Young proposed hexagonal cell transmissions for mobile phones.[27] Philip T. Porter, also of Bell Labs, proposed that the cell towers be at the corners of the hexagons rather than the centers and have directional antennas that would transmit/receive in 3 directions (see picture at right) into 3 adjacent hexagon cells.[28][29] The technology did not exist then and the radio frequencies had not yet been allocated. Cellular technology was undeveloped until the 1960s, when Richard H. Frenkiel and Joel S. Engel of Bell Labs developed the electronics.

Meanwhile, the 1956 inauguration of the TAT-1 cable and later international direct dialing were important steps in putting together the various continental telephone networks into a global network.

On 3 April 1973 Motorola manager Martin Cooper placed a cellular phone call (in front of reporters) to Dr. Joel S. Engel, head of research at AT&T's Bell Labs. This began the era of the handheld cellular mobile phone.

Cable television companies began to use their fast-developing cable networks, with ducting under the streets of the United Kingdom, in the late 1980s, to provide telephony services in association with major telephone companies. One of the early cable operators in the UK, Cable London, connected its first cable telephone customer in about 1990.

Women's usage in the 20th century

Private conversation, 1910

The telephone was instrumental to modernization. It aided in the development of suburbs and the separation of homes and businesses, but also became a reason for the separation between women occupying the private sphere and men in the public sphere.[30] This would continue to isolate women and the home.

Women were regarded as the most frequent users of the telephone. It enabled women to work in the telecommunications sector as receptionists and operators. Their autonomy was celebrated as women were able to develop new relationships and nurture pre-existing ones in their private lives. Social relations are essential in the access and usage of telephone networks.

Both historically and currently, women are predominantly responsible for the phone calls that bridge the public and private sphere, such as calls regarding doctor’s appointments and meetings.[31] This emphasizes the telephone’s impact on the social lives of women in the domestic sphere, reducing both isolation and insecurity.

21st century developments

Internet Protocol (IP) telephony, also known as Internet telephony or Voice over Internet Protocol (VoIP), is a disruptive technology that is rapidly gaining ground against traditional telephone network technologies. In Japan and South Korea up to 10% of subscribers switched to this type of telephone service as of January 2005.

IP telephony uses a broadband Internet service to transmit conversations as data packets. In addition to replacing the traditional plain old telephone service (POTS) systems, IP telephony also competes with mobile phone networks by offering free or lower cost service via WiFi hotspots. VoIP is also used on private wireless networks which may or may not have a connection to the outside telephone network.

See also


  1. ^ a b c McVeigh, Daniel P. An Early History of the Telephone: 1664-1866: Robert Hooke's Acoustic Experiments and Silent Inventions Archived 24 May 2014 at the Wayback Machine, Columbia University website. Retrieved 15 January 2013. This work in turn cites:
    • Richard Waller and edited by R.T. Gunther. "The Postthumous Works of Robert Hooke, M.D., S.R.S. 1705." Reprinted in R.T. Gunther's "Early Science In Oxford", Vol. 6, p. 185, 25 "Archived copy". Archived from the original on 24 May 2014. Retrieved 20 May 2014.CS1 maint: Archived copy as title (link) CS1 maint: BOT: original-url status unknown (link)
  2. ^ a b Jacobs, Bill. Acoustic Telephones, TelefoonMuseum.com website. Retrieved 15 January 2013. This article in turn cites:
    • Kolger, Jon. "Mechanical or String Telephones", ATCA Newsletter, June 1986; and
    • "Lancaster, Pennsylvania Agricultural Almanac for the Year 1879: How to Construct a Farmer's Telephone", John Bater's Sons.; and
    • "Telephone Experiences of Harry J. Curl as told by him to E. T. Mahood, During the summer of 1933 at Kansas City, Missouri: First Telephone Experience."
  3. ^ Grigonis, Richard. A Telephone in 1665?, TMCNet Technews website, 29 December 2008.
  4. ^ Giles, Arthur (editor). County Directory of Scotland (for 1901-1904): Twelfth Issue: Telephone (Scottish Post Office Directories), Edinburgh: R. Grant & Son, 1902, p. 28.
  5. ^ "Voicepipes and Speaking-Tubes". The Museum of Retro-Technology. 15 March 2010. Retrieved 17 October 2012.
  6. ^ Jones, R. Victor Samuel Thomas von Sömmering's "Space Multiplexed" Electrochemical Telegraph (1808-10), Harvard University website. Attributed to "Semaphore to Satellite", International Telecommunication Union, Geneva 1965. Retrieved 2009-05-01
  7. ^ Ronalds, B.F. (2016). Sir Francis Ronalds: Father of the Electric Telegraph. London: Imperial College Press. ISBN 978-1-78326-917-4.
  8. ^ Lewis Coe (1995), "The Telephone and Its Several Inventors"
  9. ^ "H.Res.269 - Expressing the sense of the House of Representatives to honor the life and achievements of 19th-century Italian-American inventor Antonio Meucci, and his work in the invention of the telephone. 107th Congress (2001-2002)". U.S. House of Representatives. Retrieved 7 February 2014.
  10. ^ Private Telegraphs, The Sydney Morning Herald, credited to The Times, 19 April 1878, p. 6.
  11. ^ Bo Leuf (2002). Peer to Peer: Collaboration and Sharing Over the Internet. Addison-Wesley. p. 15. ISBN 9780201767322.
  12. ^ Alvin K. Benson (2010). Inventors and inventions Great lives from history Volume 4 of Great Lives from History: Inventors & Inventions. Salem Press. p. 1298. ISBN 9781587655227.
  13. ^ Puskás Tivadar (1844 - 1893) (short biography), Hungarian History website. Retrieved from Archive.org, February 2013.
  14. ^ "Puskás Tivadar (1844 - 1893)". Mszh.hu. Archived from the original on 8 October 2010. Retrieved 2012-07-01.
  15. ^ "Puskás, Tivadar". Omikk.bme.hu. Retrieved 2012-07-01.
  16. ^ "Welcome hunreal.com - BlueHost.com". Hunreal.com. Archived from the original on 2012-03-16. Retrieved 2012-07-01.
  17. ^ a b c d e f g Withdrawal of National Historic Landmark Designation: Site of the First Telephone Exchange, New Haven, New Haven County, Connecticut, United States National Park Service, United States Department of the Interior, 13 April 2006. Archived 15 August 2012 at the Wayback Machine
  18. ^ "History Of The Invention Of Telephone". The Reverse Phone. 9 June 2011. Retrieved 22 April 2012.
  19. ^ "Antonio Meucci - Questions and Answers". Chezbasilio.org. Retrieved 2012-08-30.
  20. ^ http://cdrecord.org/private/tel.html
  21. ^ "Southern New England Telephone Company: The First Fifty Years, 1878-1928". Thomas J. Dodd Research Center. University of Connecticut. Archived from the original on June 9, 2008.
  22. ^ Bennett, Alfred Roslin (1895). Telephone Systems of the Continent of Europe. p. 337. Retrieved 14 June 2012.
  23. ^ "Early U.S. Telephone Industry Data". Retrieved 15 June 2012.
  24. ^ "AT&T: History: Origins". Corp.att.com. Archived from the original on 20 August 2012. Retrieved 2012-08-30.
  25. ^ "Leaders in the early spread of telephone service". Purplemotes.net. 21 March 2010.
  26. ^ http://www.porticus.org/bell/images/we-102.jpg
  27. ^ "1947 memo by Douglas H. Ring proposing hexagonal cells" (PDF). Archived from the original (PDF) on 7 February 2012. Retrieved 30 August 2012.
  28. ^ Farley, Tom; van der Hoek, Mark (1 January 2006). "Cellular Telephone Basics". PrivateLine. Archived from the original on 3 May 2012. Retrieved 22 April 2012.
  29. ^ interview of Joel S. Engel, page 17 (image 18) Archived 16 June 2007 at the Wayback Machine
  30. ^ Kramarae, edited by Cheris; Lana F. Rakow (1988). Technology and women's voices : keeping in touch (1. publ. ed.). New York: Routledge & Kegan Paul. p. 209. ISBN 0710206798. Retrieved 9 February 2014.CS1 maint: Extra text: authors list (link)
  31. ^ Kramarae, edited by Cheris; Lana F. Rakow (1988). Technology and women's voices : keeping in touch (1. publ. ed.). New York: Routledge & Kegan Paul. p. 217. ISBN 978-0710206794.CS1 maint: Extra text: authors list (link)
This article includes text from Withdrawal of National Historic Landmark Designation: Site of the First Telephone Exchange, New Haven, New Haven County, Connecticut, by the United States National Park Service, a work in the public domain.

Further reading

External links

12-channel carrier system

In the U.S. telephone network, the 12-channel carrier system was an early frequency-division multiplexing system standard, used to carry multiple telephone calls on a single twisted pair of wires, mostly for short to medium distances. In this system twelve voice channels are multiplexed in a high frequency carrier and passed through a balanced pair trunk line similar to those used for individual voice frequency connections. The original system is obsolete today, but the multiplexing of voice channels in units of 12 or 24 channels in modern digital trunk lines such as T-1 is a legacy of the system.

The twelve channel scheme was first devised in the early 1930s to provide a line spectrum covering 60 to 108 kHz for the Type J Carrier Telephone System, an equivalent four wire (on two wire facilities) open wire carrier that was used almost exclusively for interstate long haul toll telephony. This became the basic building block, the "channel group", for all succeeding long haul systems, such as Type K and all the Type L systems into the late 1970s. All long haul "channel groups" used the single-sideband/suppressed carrier heterodyne scheme that was produced by a Western Electric Type A-1 through A-6 channel bank.

The twelve channel scheme, in order to maintain some bandwidth and routing compatibility, was carried through to the short haul carriers, as well, as they started developing to eliminate voice band open wire trunk lines in the 1950s. The Bell System vacuum-tube driven N-1 Carrier of the early 1950s was the most used twelve channel carrier system, using double sideband/unsuppressed carrier operation which didn't need network timebase synchronization to maintain frequency accuracy. N-2 was similar in heterodyning scheme, but in discrete transistorized "plug-in unit" architecture, while N3 used the same frequency plan but a scheme of using single sideband with a different voice channel on each side of the carrier, a technique first seen on the 16 channel Type "O" open wire short haul carrier of the 1950s. This doubled the capacity to 24 channels, the same as a basic digital Type T PCM carrier introduced in the late 1950s, which became the now-ubiquitous "T-1" of the digital world.

Repeaters were spaced approximately 6 miles (10 km) apart, depending on wire gauge. With few exceptions, N-carriers used 19 gage unloaded toll pairs in two-wire operation. Each repeater either received from both directions at a low frequency band and sent in both directions at a higher band, or vice versa. This frequency frogging allowed equivalent four-wire operation on a single cable pair in two-wire operation.

During the period when Type N-1 was in widespread use, Lenkurt Corporation, owned and controlled by General Telephone, fielded a variant competitor, the Type BN. BN used the same pairs and repeaters as did the Bell N-CXR, but used four channel "groups," lower single-sideband heterodyning, and 24 channels per carrier, as later seen on Western Electric's Type N-3. Type BN was used at times by Bell Operating Companies after the 1956 Hush-a-phone Decision of the US Supreme Court, a landmark case which challenged AT&T's "benign monopoly" of US telephone equipment industry. Part of this settlement was for AT&T's Bell Operating Companies to buy and use small amounts of Lenkurt and Collins microwave and carrier systems. In California, Type BN was used almost exclusively to provide trunk and private line connections between Pacific Tel. & Tel. toll offices and local General Telephone end offices.


The Automatic Voice Network (AUTOVON, military designation 490-L) was a worldwide American military telephone system. The system was built starting in 1963, based on the Army's existing Switch Communications Automated Network (SCAN) system. In June 1966 the Air Defense Command voice network was cut over to the new service. In 1969, AUTOVON switching centers opened in the United Kingdom, and later in other European countries, Asia, the Middle East, and Panama. It was a major part of the Defense Communications System (DCS), providing non-secure switched voice services. The system was replaced in the early 1990s by the Defense Switched Network.

Bell Memorial

The Bell Memorial (also known as the Bell Monument or Telephone Monument) is a memorial designed by Walter Seymour Allward to commemorate the invention of the telephone by Alexander Graham Bell at the Bell Homestead National Historic Site, in Brantford, Ontario, Canada.

In 1906, the citizens of the Brantford and Brant County areas formed the Bell Telephone Memorial Association, which commissioned the memorial. By 1908, the association's designs committee asked sculptors on two continents to submit proposals for the memorial. The submission by Canadian sculptor Walter Seymour Allward of Toronto won the competition. The memorial was originally scheduled for completion by 1912 but Allward, aided by his studio assistant Emanuel Hahn did not finish it until five years later. The Governor General of Canada, Victor Cavendish, 9th Duke of Devonshire, unveiled the memorial on 24 October 1917.

Allward designed the monument to symbolize the telephone's ability to overcome great distances. A series of steps lead to the main section where the floating allegorical figure of Inspiration appears over a reclining male figure representing Man, transmitting sound through space, discovering his power to transmit sound through space, and also pointing to three floating figures, the messengers of Knowledge, Joy, and Sorrow positioned at the other end of the tableau. Additionally, there are two female figures mounted on granite pedestals representing Humanity positioned to the left and right of the memorial, one sending and the other receiving a message.

The Bell Memorial has been described as the finest example of Allward's early work. The memorial itself has been used as a central fixture for many civic events and remains an important part of Brantford's history. It was provided a heritage designation under the Ontario Heritage Act in 2005 and listed on the Canadian Register of Historic Places in 2009.

Carbon microphone

The carbon microphone, also known as carbon button microphone, button microphone, or carbon transmitter, is a type of microphone, a transducer that converts sound to an electrical audio signal. It consists of two metal plates separated by granules of carbon. One plate is very thin and faces toward the speaking person, acting as a diaphragm. Sound waves striking the diaphragm cause it to vibrate, exerting a varying pressure on the granules, which in turn changes the electrical resistance between the plates. Higher pressure lowers the resistance as the granules are pushed closer together. A steady direct current is passed between the plates through the granules. The varying resistance results in a modulation of the current, creating a varying electric current that reproduces the varying pressure of the sound wave. In telephony, this undulating current is directly passed through the telephone wires to the central office. In public address systems it is amplified by an audio amplifier. The frequency response of the carbon microphone, however, is limited to a narrow range, and the device produces significant electrical noise.

Before the proliferation of vacuum tube amplifiers in the 1920s, carbon microphones were the only practical means of obtaining high-level audio signals. They were widely used in telephone systems until the 1980s, while other applications used different microphone designs much earlier. Their low cost, inherently high output and frequency response characteristic were well suited for telephony. For plain old telephone service (POTS), carbon-microphone based telephones can still be used without modification. Carbon microphones, usually modified telephone transmitters, were widely used in early AM radio broadcasting systems, but their limited frequency response, as well as a fairly high noise level, led to their abandonment in those applications by the late 1920s. They continued to be widely used for low-end public address, and military and amateur radio applications for some decades afterward.

Connections Museum

The Connections Museum (formerly the Herbert H. Warrick Jr. Museum of Communications, originally the Vintage Telephone Equipment Museum), is located in Centurylink's Duwamish Central Office at East Marginal Way S. and Corson Avenue S. in Georgetown, Seattle, Washington. It "reveals the history of the telephone and the equipment that makes it all work." The museum was originally sponsored by the Washington Telecom Pioneers, and is now a part of the Telecommunications History Group, based in Denver, CO. It features vintage equipment from AT&T, Western Electric, Pacific Northwest Bell, USWest, and other organizations.

Invention of the telephone

The invention of the telephone was the culmination of work done by many individuals, and led to an array of lawsuits relating to the patent claims of several individuals and numerous companies. The first telephone was invented by Antonio Meucci, but Alexander Graham Bell is credited with the development of the first practical telephone.

Johann Philipp Reis

Johann Philipp Reis (German: [ʁaɪs]; January 7, 1834 – January 14, 1874) was a self-taught German scientist and inventor. In 1861, he constructed the first make-and-break telephone, today called the Reis telephone.

Number Five Crossbar Switching System

The Number Five Crossbar Switching System (5XB switch) is a telephone switch for telephone exchanges designed by Bell Labs and manufactured by Western Electric starting in 1947. It was used in the Bell System principally as a Class 5 telephone switch in the public switched telephone network (PSTN) until the early 1990s, when it was replaced with electronic switching systems. Variants were used as combined Class 4 and Class 5 systems in rural areas, and as a TWX switch.

5XB was originally intended to bring the benefits of crossbar switching to towns and small cities with only a few thousand telephone lines. The typical starting size was 3000 to 5000 lines, but the system had essentially unlimited growth capacity. The earlier 1XB urban crossbar was impractically expensive in small installations, and had difficulties handling large trunk groups. 5XB was converted to wire spring relays in the 1950s and otherwise upgraded in the 1960s to serve exchanges with tens of thousands of lines. The final 5A Crossbar variant, produced starting in 1972, was available only in sizes of 980 and 1960 lines, and generally delivered on one pallet, rather than assembled on site as usual for larger exchanges.

Number One Crossbar Switching System

The Number One Crossbar Switching System (1XB switch), was the primary technology for designing urban telephone exchanges in the Bell System in the mid-20th century. Its switch fabric used the new electromechanical crossbar switch to implement the topology of the panel switching system of the 1920s. The first 1XB system was installed in the PResident-2 office at Troy Avenue in Brooklyn, New York which became operational in February 1938.

Number One Electronic Switching System

The Number One Electronic Switching System (1ESS) was the first large-scale stored program control (SPC) telephone exchange or electronic switching system in the Bell System. It was manufactured by Western Electric and first placed into service in Succasunna, New Jersey, in May 1965. The switching fabric was composed of a reed relay matrix controlled by wire spring relays which in turn were controlled by a central processing unit (CPU).

The 1AESS central office switch was a plug compatible, higher capacity upgrade from 1ESS with a faster 1A processor that incorporated the existing instruction set for programming compatibility, and used smaller remreed switches, fewer relays, and featured disk storage. It was in service from 1976 to 2017.

Panel switch

The Panel Machine Switching System is an early type of automatic telephone exchange for urban service, introduced in the Bell System in the 1920s. It was developed by Western Electric Laboratories, the forerunner of Bell Labs, in the U.S., in parallel with the Rotary system at International Western Electric in Belgium before World War I. Both systems had many features in common.

The Panel switch was named for its tall panels which consisted of layered strips of terminals. Between each strip was placed an insulating layer, which kept each metal strip electrically isolated from the ones above and below. These terminals were arranged in banks, five of which occupied an average selector frame. Each bank contained 100 sets of terminals, for a total of 500 sets of terminals per frame. At the bottom, the frame had two electric motors to drive sixty selectors up and down by electromagnetically controlled clutches. As calls were completed through the system, selectors moved vertically over the sets of terminals until they reached the desired location, at which point the selector stopped its upward travel, and selections progressed to the next frame, until finally, the called subscriber's line was reached.

The first Panel-type exchanges were placed in service in Newark, New Jersey, on January 16, 1915 at the Mulberry central office, and on June 12 in the Waverly central office. These systems were semi-mechanical, using telephones at customer stations without a dial. Operators answered calls and keyed the station number into the panel switch, which then completed the call. The first fully machine-switching Panel systems using common control principles were placed in service in Omaha, Nebraska in December 1921, followed by the PEnnsylvania exchange in New York City in October 1922. Most Panel installations were replaced by modern systems during the 1970s. The last Panel switch, located in the Bigelow central office in Newark, was decommissioned by 1983.


The photophone is a telecommunications device that allows transmission of speech on a beam of light. It was invented jointly by Alexander Graham Bell and his assistant Charles Sumner Tainter on February 19, 1880, at Bell's laboratory at 1325 L Street in Washington, D.C. Both were later to become full associates in the Volta Laboratory Association, created and financed by Bell.

On June 3, 1880, Bell's assistant transmitted a wireless voice telephone message from the roof of the Franklin School to the window of Bell's laboratory, some 213 meters (about 700 ft.) away.Bell believed the photophone was his most important invention. Of the 18 patents granted in Bell's name alone, and the 12 he shared with his collaborators, four were for the photophone, which Bell referred to as his "greatest achievement", telling a reporter shortly before his death that the photophone was "the greatest invention [I have] ever made, greater than the telephone".The photophone was a precursor to the fiber-optic communication systems that achieved worldwide popular usage starting in the 1980s. The master patent for the photophone (U.S. Patent 235,199 Apparatus for Signalling and Communicating, called Photophone) was issued in December 1880, many decades before its principles came to have practical applications.

Reis telephone

The Reis telephone was an invention named after Philipp Reis of a telephonelike device he constructed. Reis's first successful work is dated to October 1861.

Telephone directory

A telephone directory, commonly called a telephone book, telephone address book, phone book, or the white/yellow pages, is a listing of telephone subscribers in a geographical area or subscribers to services provided by the organization that publishes the directory. Its purpose is to allow the telephone number of a subscriber identified by name and address to be found.

The advent of the Internet and smartphones in the 21st century greatly reduced the need for a paper phone book. Some communities, such as Seattle and San Francisco, sought to ban their unsolicited distribution as wasteful, unwanted and harmful to the environment.

Telephone magneto

A telephone magneto is a hand-cranked electrical generator that uses permanent magnets to produce alternating current from the rotating armature. In early telegraphy, magnetos were used to power instruments, while in telephony they were used to generate electrical current to drive electromechanical ringers in telephone sets and on operator consoles.

The Telephone Cases

The Telephone Cases, 126 U.S. 1 (1888), were a series of U.S. court cases in the 1870s and 1880s related to the invention of the telephone, which culminated in the 1888 decision of the United States Supreme Court upholding the priority of the patents belonging to Alexander Graham Bell. Those telephone patents were relied on by the American Bell Telephone Company and the Bell System—although they had also acquired critical microphone patents from Emile Berliner.

The objector (or plaintiff) in the notable Supreme Court case was initially the Western Union telegraph company, which was at the time a far larger and better financed competitor than American Bell Telephone. Western Union advocated several more recent patent claims of Daniel Drawbaugh, Elisha Gray, Antonio Meucci and Philip Reis in a bid to invalidate Alexander Graham Bell's master and subsidiary telephone patents dating back to March 1876. Had Western Union succeeded it would have immediately destroyed the Bell Telephone Company and then Western Union stood to become the world's largest telecommunications monopoly in Bell's place.

The U.S. Supreme Court came within one vote of overturning the Bell patent, thanks to the eloquence of lawyer Lysander Hill for the Peoples Telephone Company. In a lower court, the Peoples Telephone Company stock rose briefly during the early proceedings, but dropped after their claimant Daniel Drawbaugh took the stand and drawled: "I don’t remember how I came to it. I had been experimenting in that direction. I don’t remember of getting at it by accident either. I don’t remember of anyone talking to me of it".In this case the court affirmed several other lower court cases: Dolbear et al. v American Bell Tel. Co., 15 Fed. Rep 448, 17 Fed. Rep. 604, Molecular Te. Co. et al. v American Bell Tel. Co. 32 Fed. Rep 214, People's Tel. Co. et al. v American Bell Tel. Co., 22 Fed. Rep. 309 and 25 Fed. Rep. 725. Well reversing American Bell Tel Co. et al. v Molecular Tel. Co et al. 32 Fed Rep. 214.

Bell’s second fundamental patent expired on January 30, 1894, at which time the gates were then opened to independent telephone companies to compete with the Bell System. In all, the American Bell Telephone Company and its successor, AT&T, litigated 587 court challenges to its patents including five that went to the U.S. Supreme Court, and aside from two minor contract lawsuits, never lost a single one that was concluded with a final stage judgment.

Timeline of the telephone

This timeline of the telephone covers landline, radio, and cellular telephony technologies and provides many important dates in the history of the telephone.

Traffic Service Position System

"TSPS" redirects here. For the school, see The Sheffield Private School.The Traffic Service Position System (TSPS) was developed by Bell Labs in Columbus, Ohio to replace traditional cord switchboards. The first TSPS was deployed in 1969 and used the Stored Program Control-1A CPU, "Piggyback" twistor memory (a proprietary technology developed by Bell Labs similar to core memory) and Insulated Gate Field Effect Transistor solid state memory devices similar to dynamic random access memory.

Transatlantic communications cable

A transatlantic telecommunications cable is a submarine communications cable connecting one side of the Atlantic Ocean to the other. In the 19th and early 20th centuries each cable was a single wire. After mid-century, coaxial cable came into use, with amplifiers. Late in the century, all used optical fiber, and most now use optical amplifiers.

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.