Telephone

History

Throughout history, people have devised methods for communicating over long distances. The earliest methods involved crude systems such as drum beating or smoke signaling. These systems evolved into optical telegraphy, and by the early 1800s, electric telegraphy. The first simple telephones, which were comprised of a long string and two cans, were known in the early eighteenth century.

A working electrical voice-transmission system was first demonstrated by Johann Philipp Reis in 1863. His machine consisted of a vibrating membrane that opened or closed an electric circuit. While Reis only used his machine to demonstrate the nature of sound, other inventors tried to find more practical applications of this technology. They were found by Alexander Graham Bell in 1876 when he was awarded a patent for the first operational telephone. This invention proved to revolutionize the way people communicate throughout the world.

Bell's interest in telephony was primarily derived from his background in vocal physiology and his speech instruction to the deaf. His breakthrough experiment occurred on June 2, 1875. He and his assistant, Thomas Watson, were working on a harmonic telegraph. When a reed stuck on Watson's transmitter an intermittent current was converted to a continuous current. Bell was able to hear the sound on his receiver confirming his belief that sound could be transmitted and reconverted through an electric wire by using a continuous electric current.

The original telephone design that Bell patented was much different than the phone we know today. In a real sense, it was just a modified version of a telegraph. The primary difference was that it could transmit true sound. Bell continued to improve upon his design. After two years, he created a magnetic telephone which was the precursor to modern phones. This design consisted of a transmitter, receiver, and a magnet. The transmitter and receiver each contained a diaphragm, which is a metal disk. During a phone call, the vibrations of the caller's voice caused the diaphragm in the transmitter to move. This motion was transferred along the phone line to the receiver. The receiving diaphragm began vibrating thereby producing sound and completing the call.

While the magnetic phone was an important breakthrough, it had significant drawbacks. For example, callers had to shout to overcome noise and voice distortions. Additionally, there was a time lapse in the transmission which resulted in nearly incoherent conversations. These problems were eventually solved as the telephone underwent numerous design changes. The first phones made available to consumers used a single microphone. This required the user to speak into it and then put it to the ear to listen. Thomas Edison introduced a model that had a moveable listening earpiece and stationary speaking tube. When placing a call, the receiver was lifted and the user was connected directly to an operator who would then switch wires manually to transmit. In 1878, the first manual telephone exchange was opened. It served 21 customers in New Haven, Connecticut. Use of the telephone spread rapidly and in 1891, the first automatic number calling mechanism was introduced.

Long-distance service was first made available in 1881. However, the transmission rates were not good and it was difficult to hear. In 1900, two workers at Bell System designed loading coils that could minimize distortions. In 1912, the vacuum tube was adapted to the phone as an amplifier. This made it possible to have a transcontinental phone line, first demonstrated in 1915. In 1956, a submarine cable was laid across the Atlantic to allow transatlantic telephone communication. The telecommunication industry was revolutionized in 1962 when orbiting communication satellites were utilized. In 1980, a fiber-optic system was introduced, again revolutionizing the industry.

Background

Telephones still operate on the same basic principles that Bell introduced over one hundred years ago. If a person wishes to make a call, they pick up the handset. This causes the phone to be connected to a routing network. When the numbers are pressed on a touch-tone keypad, signals are sent down the phone line to the routing station. Here, each digit is recognized as a combination of tone frequencies. The specific number combination causes a signal to be sent to another phone causing it to ring. When that phone is picked up, a connection between the two phones is initiated.

The mouthpiece acts as a microphone. Sound waves from the user's voice cause a thin, plastic disk inside the phone to vibrate. This changes the distance between the plastic disk and another metal disk. The intensity of an electric field between the two disks is changed as a result and a varying electric current is sent down the phone line. The receiver on the other phone picks up this current. As it enters the receiver, it passes through a set of electromagnets. These magnets cause a metal diaphragm to vibrate. This vibration reproduces the voice that initiated the current. An amplifier in the receiver makes it easier to hear. When one of the phones is hung up the electric current is broken, causing all of the routing connections to be released.

Elisha Gray was Alexander Graham Bell's principle rival, first for invention of the harmonic telegraph and then of the telephone. He was a prolific inventor, granted some 70 patents during his lifetime. Born in Barnesville, Ohio, on August 2, 1935, and brought up on a farm, Gray had to leave school early when his father died but later continued his studies at Oberlin College, where he concentrated on physical sciences, especially electricity, and supported himself as a carpenter.

After leaving Oberlin, Gray continued his electrical experiments, concentrating on telegraphy. In 1867, he patented an improved telegraph relay, and later, a telegraph switch, an "annunciator" for hotels and large business offices, a telegraphic repeater, and a telegraph line printer. He also experimented with ways to transmit multiple, separate messages simultaneously across a single wire, a subject that was also engaging the efforts of Bell. Gray prevailed, filing his harmonic telegraph patent application in February 1875, two days before Bell's similar application.

Gray now began investigating ways to transmit voice messages, soon developing a telephone design that featured a liquid transmitter and variable resistance. In one of the most remarkable coincidences in the history of invention, Gray filed notice of his intent to patent his device on February 14, 1876—just two hours after Bell had filed his own telephone patent at the same office. Western Union Telegraph Company purchased the rights to Gray's telephone and went into the telephone business; the Bell Telephone Company launched a bitter lawsuit in return.

Meanwhile, Gray had been a founding partner in 1869 of Gray and Barton, an electric-equipment shop in Cleveland, Ohio. This became Western Electric Manufacturing of Chicago in 1872, which evolved into Western Electric Company, which, ironically, became the largest single component of Bell Telephone in 1881.

The system of transmission presented describes what happens during a local call. It varies slightly for other types of calls such as long distance or cellular. Long distance calls are not always connected directly through wires. In some cases, the signal is converted to a satellite dish signal and transmitted via a satellite. For cellular phones, the signal is sent to a cellular antenna. Here, it is sent via radio waves to the appropriate cell phone.

Raw Materials

A variety of raw materials are used for making telephones. Materials range from glass, ceramics, paper, metals, rubber and plastics. The primary components on the circuit board are made from silicon. The outer housing of the phone is typically made of a strong, high-impact resistant polymer. To modify the characteristics of this polymer, various fillers and colorants are used. The speakers require magnetic materials.

Design

Modern telephones come in many shapes and sizes, but they all have the same general features. They consist of a single handset which contains both the transmitter and receiver. The handset rests on the base when the phone is not in use. They also have a dialing system which is either a rotary dial or a touch-tone keypad. Recently, rotary phones have been phased out in favor of the more useful keypad. To alert the consumer that they have an incoming call, phones are equipped with ringers. A wide variety of specialized phones are also produced. Speaker phones are made to allow the consumer to carry on a telephone conversation without holding the handset. Cordless phones are also available. These models do not require direct connection of the handset to the base. Instead the user's voice is converted to radio waves and then sent to the phone base. This, in turn, gets converted to an electric signal and sent down the phone lines. Another type of common phone is the cellular phone. These phones use radio waves and an antenna system to communicate between phones.

The Manufacturing
Process

Since there are so many different parts that go into making a telephone, the components are typically produced by different companies and then assembled by the phone manufacturer. The main components include the internal electronics, the handset, and the various plastic parts.

Plastic parts

• 1 To produce the plastic parts like the base, handset casing, and push buttons, injection molding is typically done. In this process, pellets of plastic polymer are put into the hopper of an injection molding machine. They then pass through a hydraulically controlled screw and are melted. While the screw rotates, the melted plastic is moved through a nozzle and injected into a mold. Just prior to this injection, the two halves of a mold are brought together to form a cavity which matches the shape of the telephone part. While inside the mold, the plastic is held under pressure for a set amount of time and then allowed to cool. As it cools, it hardens and forms into the shape of the part. This mold is coated with chromium to create a shiny surface.
• 2 After a short while, the mold halves are opened and the part is ejected. The mold then closes again and the process begins again. At this point in process, many of the parts are manually inspected to ensure that no significantly damaged parts are used. If there are damaged parts, they are set aside to be remelted and reformed into new parts.

Internal electronics

• 3 The electronic components of the telephone are sophisticated and use the latest in electronic processing technology. The circuit board is produced the same way that boards are made for other types of electronic equipment. The process begins with a board made of non-conducting material that has the electronic configuration printed on it using a conducting material. This board is then passed through a series of machines that place the appropriate chips, diodes, capacitors and other electronic parts in the appropriate places. To prevent damage caused by dust, the process is completed in a specially cleaned room. When completed, it is sent to the next step for soldering.
• 4 To affix the electronic parts to the board, a wave soldering machine is used. Before being put into the machine, the board is washed to remove contaminants. Upon entering, the board is heated using infrared heat. The underside of the board is passed over a wave of molten solder and through capillary action, all of the necessary spots are filled. As the board is allowed to cool, the solder hardens and the pieces stay in place. This creates an electrical connection between the printed circuits and the components.

Assembly and Packaging

• 5 The individual parts are assembled both automatically and manually. The transmitter and receiver are put together by machines. These parts are then fed onto the main assembly line and inserted into the molded headset. Similarly, the internal electronics, including the touch-tone pad, are inserted into the main housing and attached with screws. The headset is then put on the phone base and the phone chord may also be put on.
• 6 After all of the phone pieces are assembled, the completed phones are put in final packaging. Typically, they are wrapped in plastic and put in boxes. A packaging material such as polystyrene is also included to protect the device from damage during shipping. An owner's manual or other literature is included and the box is sealed with tape. The boxes are stacked on pallets, shipped to distributors and finally, customers.

Quality Control

To ensure the quality of each telephone, visual and electrical inspections are done throughout the entire production process and most flaws are detected. Additionally, the each completed phone is tested to make sure it works. Often these tests are done under different environmental conditions such as excessive heat and humidity to simulate the extremes that are experienced in a real life setting. Plastic parts are given torture tests to ensure they will still function even after a level of consumer abuse. For example, the numbers on a touch tone pad are put under a rubber-finger that taps the buttons enough times that it equals forty years of dialing. Since many of the parts that make up the telephone are produced by subcontractors, telephone manufacturers rely heavily on these suppliers for good quality. To ensure consistent manufacturing, most telephone makers set quality specifications for individual parts that the suppliers must meet.

The Future

Telephone technology is improving rapidly. In the future, cordless phones will be designed to be smaller and lighter. They will have wider transmission and better reception ranges. The sound quality will also be improved. Other technologies that integrate the phone with computers and cable television will be commonplace. Dialing systems will also be improved. In a recent demonstration, one company showed a technology that accepted voice command to dial a phone number.

Where to Learn More

Books

Bigelow, Stephen. Understanding Telephone Electronics New York: Butterworth-Heinemann, 1997.

Noll, A. Introduction to Telephones and Telephone Systems. New York: Artech House Publishers, 1998.

Grosvenor, E and M. Wesson. Alexander Graham Bell: The Life and Times of the Man Who Invented the Telephone. Harry N. Abrams Inc., 1997.

Periodicals

Woolley, S. "Dial tones? No, Web tones." Forbes (January 26, 1998).

—PerryRomanowski

telephone device for communicating sound, especially speech, usually by means of wires in an electric circuit. The telephones now in general use evolved from the device invented by Alexander Graham Bell and patented by him in 1876 and 1877. Although Bell is recognized as the inventor, his telephone was preceded by many attempts to produce such an instrument. The principles on which it is based, and effective model instruments, were developed by different men at so nearly the same time that there are disputes about priority. In Bell's instrument, an electric current varied in intensity and frequency in accordance with sound waves. The sound waves caused a thin plate of soft iron, called the diaphragm, to vibrate. The vibrations disturbed the magnetic field of a bar magnet placed near the diaphragm, and this disturbance induced an electric current in a wire wound about the magnet. That current, when transmitted to a distant identical instrument, caused the diaphragm in it to vibrate, reproducing the original sound. Bell's instrument was thus both transmitter and receiver. The first notable improvement of the Bell telephone differentiated the transmitting instrument from the receiving instrument. Many other inventions have improved the telephone.

The switches used to route telephone calls, which were once electromechanical, are now largely replaced by sophisticated digital electronic switching systems. The electronic switches are much more flexible because they can be programmed to provide new services. The latest generation of switches have made a number of new features possible. Users, for example, can read the telephone number of the calling party on a display device if they choose to subscribe to a "caller ID" service. In "call waiting," audio signals let a person already on a telephone know that someone else is trying to reach that person. Subscribers can also program the telephone switches to forward their calls automatically to another number ( "call forwarding" ). Other features include voice mailboxes and the ability to make three-way conference calls.

The problems associated with long-distance and intercity telephone service have been met with increasing success. The telephone lines used include the ordinary open wire lines, lead-sheathed cables consisting of many lines, and coaxial and fiber-optic cables. Coaxial and fiber-optic cables are typically placed underground, but other cables may be either overhead or underground. Transmission of telephone messages over long distances is often accomplished by means of radio and microwave transmissions. In some cases microwaves are sent to an orbiting communications satellite (see satellite, artificial ) from which they are relayed back to a distant point on the earth. Cellular telephone systems allow small, low-power portable radio transceivers access to the telephone network; some cellular models provide access to the Internet. The incorporation of microelectronics and digital technology has led to the inclusion of unrelated applications in telephones, such as alarm clocks, calculators, and voice memos for recording short verbal reminders. A camera phone is a cellular phone that has photo taking and sending (to another camera phone or computer) capability. Similarly, a videophone transmits and receives real-time video images.

With the advent of the Internet , computer programs have been developed that allow voice communications across long distances, bypassing conventional carriers. The programs, which often require a computer equipped with a telephone or cable modem , microphone, and speakers, compress the voice message into digital signals. In other cases, a special adapter is used to allow a standard telephone to access the Internet directly though a cable modem or other broadband connection, or an Internet telephone (IP phone) may be used instead. The digital signals may be transmitted over the Internet to another computer, which must have another copy of the same program, or to a telephone. If a connection is established with another computer, the second program decompresses the digital signals and plays the sound almost instantaneously. The advantage of using the Internet is that under current tariffs no long-distance charges accrue on a computer to computer call, regardless of the length of the conversation. The disadvantages are the inferior sound quality on dialup connections and, in some cases, the need to have computers that are running the same program and the need to establish a connection between those computers.

In 1984 a federal court ordered American Telephone and Telegraph Company (AT&T) to divest its Bell Telephone operating companies (the "Baby Bells" ) after the court ruled that AT&T held a monopoly over U.S. telephone service. Since then, the regional operating companies and new competitors for long-distance service have grown through acquisitions and mergers. By 2007, AT&T (formerly SBC Communications, a Baby Bell, which acquired AT&T and adopted the name, and then merged in 2006 with Bell South, another Baby Bell) was the largest U.S. long-distance provider, followed by Verizon Communications (a Baby Bell that merged with MCI), and Sprint. Meanwhile, the seven Baby Bells that had been formed in 1984 were reduced to three, AT&T, Verizon, and Qwest Communications International. The distinctions between types of telephone providers, which had been created by the AT&T breakup, had disappeared, with telephone companies offering local and long-distance service in various locations, and owning wireless carriers and offering high-speed Internet service as well. At the same time these companies were also facing increasing challenges from cable television companies that offered Internet-based (VoIP) phone service over a broadband connection and independent VoIP companies, such as Vonage and Skype.

The primary regulator of telephone service in the United States is the Federal Communications Commission . The International Telecommunication Union coordinates aspects of international transmissions.

Bibliography: See T. B. Costain, Chord of Steel: The Story of the Invention of the Telephone (1960); A. M. Noll, Introduction to Telephones and Telephone Systems (2d ed. 1991).

Telephone

The word telephone comes from two Greek words, tele, meaning "distant," and phone, meaning "sound." Thus, a telephone is a device for carrying sounds over long distances. Many children are familiar with toy telephones that can be made with two tin cans joined by a taunt string or thin wire. When one person speaks into one can, sound vibrations are carried along the string or wire from the speaker's can to the listener's can. If the listener then places his or her ear next to the receiving can, the sound vibrations are converted back to an audible signal.

History

The first working telephone appears to have been invented by German inventor Johann Philipp Reis (1834–1874) in 1863. Reis constructed his telephone simply as a scientific toy, however, to demonstrate the nature of sound. He never made any attempt to convert the instrument to commercial use.

The first operational telephone was patented and produced in the United States in 1876 by American inventor Alexander Graham Bell (1847–1922). In a quirk of fate, American inventor Elisha Gray (1835–1901) filed his patent for a telephone on February 14,1876, only two hours after Bell had filed his own patent for an essentially identical device. That two-hour difference was sufficient for Bell to receive credit as being the inventor of the telephone, although Gray deserves equal credit.

Operation of the telephone

A telephone consists of four basic parts: a source of electrical current, such as a battery; conducting wires, usually made of copper; a transmitter; and a receiver. The transmitter consists of the mouthpiece into which a person speaks when placing a telephone call. The transmitter has a thin metal disk called a diaphragm inside it. Behind the diaphragm is a container that holds granules of carbon. When a person speaks into the transmitter, the diaphragm begins to vibrate. This vibration forces carbon granules into contact with each other, which varies the electrical resistance. An electric current from the source flows through the granules and into the external circuit.

The form of the current that flows out of the transmitter depends on the kinds of sound spoken into the transmitter. A loud sound presses the carbon granules together more tightly, causing the electrical resistance to drop, and a stronger electric current is produced. A quiet sound produces a weaker current. The tone of the speaker's voice also is reflected in the kind of sound waves produced and, therefore, on the kind of electric current that is created. The electric current sent out across the telephone lines, then, is a copy of the sounds made by the person's voice.

At the receiving end of the telephone line, this process is repeated in reverse order. Electric current flows into an electromagnet that pulls on the diaphragm in the receiver. The strength and nature of the electric current determines how strongly the diaphragm is pulled back and forth. As the diaphragm is pulled by the electric current, it sets up vibrations that can be detected as sound waves. Those sound waves are identical to the ones originally sent out through the transmitter.

Wireless telephone systems

The system described above requires wires to carry electrical signals from one telephone to another. As telephone usage became popular in the early part of the twentieth century, the air above urban areas became clogged with mazes of telephone wire systems. Eventually, many of these systems were brought together into large cables and buried underground.

The 1970s saw the first widespread use of wireless telephone systems in the United States. A wireless telephone system is one in which the electrical signals produced by a telephone transmitter are attached to a radio signal, similar to the one used to transmit radio broadcasts. Those radio signals can then be transmitted from one tower to another, without the need for wires. Cordless, mobile, and cellular telephones perform all the same functions as conventional telephones but use radio waves instead of wires.

The convenience and efficiency of wireless telephone communication is the reason behind the impressive growth of this service. In 1984, there were approximately 90,000 cellular telephone subscribers in the United States. By 1990, the number of subscribers had reached 4.4 million. And by the beginning of the twenty-first century, that number had ballooned to more than 13 million. The inevitable future expansion of cellular telephone communication on a global scale will be based on employing low-altitude, low-weight satellites.

At present, voice communication and data communication exist separately. As technologies become more advanced, the best of both worlds will be integrated into a multimedia telecommunications network. Multimedia will enable people to combine any media they need to send, receive, or share information in the form of speech, music, messages, text, data, images, video, animation, or even varieties of virtual reality. The emerging capabilities offered by a unified, intelligent telecommunications network will gradually transform the way people interact, work, and learn.

[See also Cellular/digital technology ]

TELEPHONE

TELEPHONE. The telephone, a speech transmission device, dates from 1876, the year Alexander Graham Bell patented his "Improvements in Telegraphy." Many inventors had been experimenting with acoustics and electricity, among them Thomas Edison, Emil Berliner, and Elisha Gray. Each of these men, as well as Bell's assistant Thomas Watson, contributed modifications that resulted in the telephone we recognize today. Technology has advanced, but the fundamental principles remain the same.

When Bell Telephone Company formed to market its product in 1877, the telegraph was the reigning telecommunication service. Coast-to-coast communication had been possible since 1861, and 2,250 telegraph offices spanned the country. Earlier that year, Western Union had been offered the Bell patent but refused it, only to buy telephone technology from others. Although Bell held the patent for the device, 1,730 other companies were making telephones.

In 1882, the American Bell Telephone Company won a court judgment against Western Union and gained controlling

interest in the company, an event that paved the way for modern telephone systems. In 1885, Bell formed a subsidiary, American Telephone & Telegraph (AT&T), which provided a network to which Bell-licensed companies could connect. For the first time, long-distance calling became possible.

As the twentieth century progressed, the importance of telephone service in the daily lives of Americans increased. The Bureau of the Census estimated that in 1920,35 percent of households had telephones. Fifty years later the figure had risen to 90.5 percent. The Bell System manufactured and installed all telephone equipment and provided all the services. As a national monopoly, it had regulated rates. It was often written that Bell was the best telephone system in the world. The 1877 technology start-up had become the largest privately owned industry in United States history with more than 1 million employees and $152 billion in assets in 1983.

However, as the 1960s drew to a close, complaints of poor service and of "Ma Bell's" monopoly attracted government attention. In 1974, the Department of Justice filed an antitrust suit against AT&T that culminated in a 1984 court order that deregulated the industry. Bell Systems had lost its empire, but its pioneering engineers left an indelible mark on the world.

Bell Telephone announced the first transcontinental telephone service at the San Francisco World's Fair in 1915. Radiotelephone service to other countries and ships at sea was available after 1927. A transatlantic cable was laid in 1956. The transmission of calls by microwave began soon after World War II (1939–1945), and Bell Laboratories initiated satellite communications with the launch of Telstar in 1962.

The Bell Systems invention that had the most dramatic impact on the world was the transistor. Unveiled in 1948, it made small electronic devices possible. The transistor was vital to the development of hearing aids, portable radios, and the personal computer.

AT&T introduced modems for data transmission between computers over telephone lines in 1958. A Department of Defense computer network project from 1969 (ARPANET) developed into the Internet by 1992, and the popular World Wide Web appeared in 1994. By 2001,143 million Americans, more than half the population, were communicating online, sending data and audio and video transmissions. Eighty percent of them re-lied on telephone dial-up connections.

BIBLIOGRAPHY

Grosvenor, Edwin, and Morgan Wesson. Alexander Graham Bell: The Life and Times of the Man Who Invented the Telephone. New York: Abrams, 1997.

Gwanthmey, Emily, and Ellen Stern. Once Upon a Telephone: An Illustrated Social History. New York: Harcourt Brace, 1994.

Katz, James Everett. Connections: Social and Cultural Studies of the Telephone in American Life. New Brunswick, N.J.: Transaction, 1999.

Noll, A. Michael. Introduction to Telephones and Telephone Systems. Norwood, Mass.: Artech House, 1999.

Christine M.Roane

See alsoAT&T ; Internet ; Telecommunications .

TELEPHONES IN THE AGE OF TECHNOLOGY

TV on the Front

The TV phone was first described in the popular press in 1950. The U.S. Army saw a need for a voice communicator that could cover long distances and include the capability of sending pictures at the same time. For example, an infantry commander near the front lines might want to call headquarters and point on a map to show where enemy positions were located to request artillery assistance. Such a capability would require the ability to link a telephone and a television video screen. Producing a live television show required lots of fancy gadgetry that was not applicable for field use. Moreover, the telephone lines used by the military could be secured, but live television broadcasts could not. Thus, a telephone TV was superior to a field TV transmitter,

A Soundproof Booth

The army solved this problem by developing a TV phone booth. It was first displayed at the U.S. Army Signal Corps in Fort Monmouth, New Jersey. A person could enter the booth and sit in a specific location. The receiving party would enter a similar booth at another location. The booth included an overhead TV screen, a telephone, and a TV camera pointed at the seat. Special lamps were required for the video image. Maps, charts, and the like could be held in front of the camera while the parties conversed on the phone about them.

World's Fair

The TV phone never became widely used, probably because of the expense and the need to have a special booth during the operation of the equipment. At the 1964 World's Fair in New York, one of the most popular exhibits was a series of AT&T booths on the fairground. People could sit in a booth, call another booth at the fair, and watch each other while they talked—the TV phone.

Radio Phone

In an age of cellular phones when people routinely place calls from their cars, it is difficult to imagine that the radio telephone was considered a radical concept in the 1950s. In fact, it was developed because of a pressing need. Many people lived in rural areas where phone lines did not yet extend, and they wanted telephone service. Building the poles and wires required to provide phone service to these areas was an expensive prospect.

REA

In 1952 the Rural Electrification Administration proposed a radio telephone. Their Technical Standards Division worked with the General Electric Company to build such a system on a small scale and test it for efficiency and economy. The radio telephone connected Chancellor and Alsop, Virginia, about ten miles apart. The voice was converted to a radio signal at the exchange in one town and was received at the exchange in the other. The signal was then converted back to phone circuitry and sent to the receiver (earpiece) of the second caller.

Answering Machine

In 1951 Assen Jordanoff and Norman Robin of New York City developed a special phone attachment. It could receive calls and record them even if no one answered the phone. It could also record an entire phone conversation by both parties. Today, we call the device a telephone answering machine—or a wiretap.

Sources:

Science Digest (April 1951): 96;

Popular Science, 157 (August 1950): 81;

Popular Mechanics, 98 (August 1952): 207.

telephone exchanges opened in Dublin and Belfast in 1880, only four years after Bell's first transmission. Dublin–Belfast trunk routes were installed in 1884. The first submarine telephone cable, laid from Port Patrick in Scotland to Donaghadee, Co. Down, in 1893, cost £20,000. By 1900 there were 56 exchanges in Ireland. In 1912 the Post Office took over the service. Following partition, two separate systems emerged on the island. By 1930 only Co. Donegal and western Mayo remained unconnected. The first automatic exchange opened in Dublin in 1927, followed, in the north, by Groomsport, Co. Down, in 1929, and Belfast in 1935. During the Second World War, both networks were urgently upgraded for security reasons. In the Irish Free State, in 1945, 107 exchanges gave continuous service to 23,700 subscribers, with a further 732 exchanges on restricted‐hour service to 5,900 subscribers. The first transatlantic telephone cable was laid in 1956. In 1957–8, Subscriber Trunk Dialling began in Athlone and Cork. Belfast switched to STD in 1961. Dublin's first international telephone exchange opened in 1971. By 1977 there were 250,000 subscribers in Northern Ireland. In 1980 responsibility for the telephone service in Northern Ireland, as in the rest of the UK, was privatized and transferred to British Telecom. The following year, there was a similar transfer of the Republic's phone services to Telecom Éireann.

Peter Collins

tel·e·phone / ˈteləˌfōn/ • n. 1. a system that converts acoustic vibrations to electrical signals in order to transmit sound, typically voices, over a distance using wire or radio. ∎  an instrument used as part of such a system, typically a single unit including a handset with a transmitting microphone and a set of numbered buttons by which a connection can be made to another such instrument. 2. a game in which a message is distorted by being passed around in a whisper. Also called Chinese whispers. • v. [tr.] call or speak to (someone) using the telephone: he had just finished telephoning his wife. ∎  [intr.] make a telephone call: she telephoned for help. ∎  send (a message) by telephone: Barbara had telephoned the news. DERIVATIVES: tel·e·phon·er n. tel·e·phon·ic / ˌteləˈfänik/ adj. tel·e·phon·i·cal·ly / ˌteləˈfänik(ə)lē/ adv.

TELEPHONES

Many Advances

The 1920s were a period of continuous advancement in telephone technology, beginning with the first completely automatic switching office, established in Omaha, Nebraska, in 1921. During that same year the first deep-sea telephone cable was laid, between Key West, Florida, and Havana, Cuba. (It is not to be confused with submarine cables for telegraph signals which had been laid since the 1850s on the ocean floor.) In 1926 American telephone transmitters and receivers were first placed in the same unit, the handset, while in 1929 telephone linemen began using the power-driven auger to bore holes for telephone poles—a great advance over hand digging.

Source:

C. D. Hanscom, ed., Dates in American Telephone Technology (New York: Beil Telephone Laboratories, 1961).

telephone Instrument that communicates speech sounds over a distance by means of wires or microwaves. In 1876, Alexander Graham Bell invented a prototype, which employed a diaphragm of soft iron that vibrated to sound waves. These vibrations caused disturbances in the magnetic field of a nearby bar magnet, causing an electric current of fluctuating intensity in the thin copper wire wrapped around the magnet. This current could be transmitted along wires to a distant identical device that reversed the process to reproduce audible sound. Later improvements separated the transmitter from the receiver, and replaced the bar magnet with batteries. See also mobile telephone

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