Telephone

views updated May 29 2018

Telephone

Invention and historical development of the telephone

Telephone set

Telephone network

Quality of telephone communication

Wireless telephone systems

Modern developments in telephony

Resources

The telephone (or simply, phone) is a telecommunications instrument that sends and receives sound such as voice messages and data across a certain distance. The term telephone is from the Greek roots tele, which means afar, and phone, which means voice or sound). In a broad sense, the telephone is a specific type of telecommunications that permits people to carry direct conversations over almost any distance.

The articulate speech is transmitted in a form of modulated electric current propagating along conductors or radio waves. The apparatus used for converting the verbal sounds into electromagnetic signals and vice versa is called a telephone set and is also commonly referred to as a telephone. Telephone communication is one of the most widespread and expeditious forms of communication. It has proved to be invaluable for an exchange of information in all areas of human life, whether it is business, government, science, public health, personal services, or social contacts. There were about 200,000 telephones in the world in 1887, approximately 30 million in 1928, 118 million in 1958, and more than 330 million in 1975. According to the University of California at Berkeley (School of Information Management and Systems), in 2004, it is estimated that over 1.3 billion main telephone lines exist in the world.

The general concept of the telephone as a system involves a number of elements. First, there is the telephone apparatus itself. Next, there is a variety of means for conveying the electromagnetic signals over distances (transmission paths). Third, the transmission paths are arranged in multi-leveled structures (networks) in a way that permits to interconnect (switch) any desired telephone sets upon request. And, finally, there are signaling facilities for directing the switching operations, alerting the person called, and clearing the circuits upon the completion of the call.

The scientific and technological discipline that studies and develops all of the telephone-systems constituents is called telephony. Many problems in telephony draw on the principles and techniques of the electromagnetic theory, the theory of linear and nonlinear circuits, the probability theory, and the queuing theory.

Invention and historical development of the telephone

Electrical telecommunication originated in the nineteenth century, with the invention of the telegrapha method of transferring intelligence between distant places through metallic wires in a form of spaced bursts of electricity. A sender, using a special letter code, produced regulated electrical pulses in a circuit. These signals were converted at the receiving end into a pattern of sound clicks, which was decoded by an operator or an automatic device. The next logical step beyond sending of non-articulate messages was the instantaneous transmission of conversation over wires. The intricate and very individual nature of sounds produced by the human vocal cords with the participation of the lips, as well as of the oral and nasal cavities, made this task difficult to accomplish. Articulate (spoken) speech involves not only the elementary sounds and their assembly into syllables, words, and sentences, but also infinite variations in accent, emphasis, intonation, and voice timbre characteristics of no importance for other types of communication.

The inventor of the telephone is not entirely agreed upon. Among the inventors who have been awarded the honor include American Scottish-Canadian scientist and inventor Alexander Graham Bell (1847 1922), American electrical engineer Elisha Gray (1835 1901), Italian inventor Antonio Mencci (18081896), and German inventor Johann Philipp Reis (1834 1874). In fact, they all spent time and effort researching and developing the telephone. The accomplishments of Bell will be discussed here.

By no chance, the invention of a way to transmit the human voice electrically was made by a man deeply involved in the study of vocal physiology and the mechanics of speech. A native of Scotland, Alexander Graham Bell inherited from his father, who was a famous professor of elocution and an author of several textbooks on speech correction, a profound interest in speech and hearing theory. He put his knowledge to work primarily for the teaching of the deaf. Being interested in electricity, Bell set up a little laboratory and experimented on transmission of sound tones over an electric circuit in an attempt to make a harmonic telegrapha device capable of sending multiple telegraph messages simultaneously over the same wire. On the basis of his experimental observations, Bell gradually came to the conclusion that oscillations of air pressure (sound waves) could be used to modulate the intensity of electric current in a circuit. Using his knowledge of ear anatomy, Bell attached one end of a metallic organ reed to a thin diaphragm intended to simulate the eardrum. In presence of even weak air-pressure variations caused by the human voice, the diaphragm forced the metallic reed to oscillate in front of the electromagnet and, therefore, to undulate the electric current in the circuit.

Telephones successfully served the public for almost 23 years before scientists could explain theoretically why the telephone worked. Bells perception of an analog relationship between sound pressure and electromotive force was one of the most fascinating examples of the ingenious intuition in the history of technological discoveries.

Bell first started testing his device for voice transmission in June 1875, and patented it nine months later. The demonstration of the working apparatus at the Philadelphia Centennial Exposition attracted substantial public interest, which helped to raise some additional monetary funds. On August 1, 1877, with Bells four patents as a tangible basis for a wide manufacturing of a speaking telephone, the Bell Telephone Company was formed. Bell outlined a general concept of a telephone system as a universal means of voice communication between individuals, at any time, from any location, and without any special skill requirements. This concept might seem obvious today, but it was far in advance of any existing techniques of its time. Giant technological and organizational efforts were required to make Bells vision of a telephone communication a reality.

The number of existing telephones at that time were 778, but rapidly growing demand presented the challenge of operating the existing telephone while producing new ones. The first telephone subscribers were directly connected to each other. Under such arrangement, a community of 100 subscribers used 9,900 separate wire connections. For 1,000 subscribers the number of needed wire connections was more than 100 times bigger. The evident impracticality of full-time point-to-point connections stimulated the idea of a central office, or exchange. All the telephone sets in a particular area, instead of being wired permanently to each other, were connected to the same central office, which could establish a temporary link between any two of them on demand. Trained operators on a switchboard initially performed the process of line connecting and disconnecting (switching). However, with more and more telephones coming into use the manual switching was becoming increasingly complex. In 1891, the first automatic switching system was introduced.

As local telephone lines emerged and expanded, the idea of the creation and commercial operation of long distance telephone communication became a necessity. Unfortunately, the already existing telegraph lines were of little use for this purpose. Feeble electric currents used in telephony were rapidly dissipated (attenuated) on their way through iron wires. Compensating for attenuation was one of the main problems of telephony during its first 50 years. Considerable success in reducing the attenuation was achieved by using copper in place of iron wire. The innovation extended the limits of the voice transmission through bare wires to a distance between Boston, Massachusetts, and Chicago, Illinois1,180 mi (1,900 km)in 1893. Later, the effectiveness of wire lines was crucially increased by inserting inductances, or loading coils, at regular distances in a circuit. For crossing small bodies of water, telephone lines were laid in a form of insulated cables instead of bare wires. The invention of radio transmission at the beginning of the twentieth century led to the development of wireless telephone links and accelerated creation of the worldwide telephone system.

Long-haul facilities grew swiftly. In 1900, toll lines totaled 621,000 mi (1 million km) of wire. It took only 25 years to increase this number by a factor of ten. In 1925, almost one-half of the long-distance circuits were cable. The first transatlantic telephone cable (TAT-1) became operational in 1956. Nine years later, the first transatlantic telephone satellite Earlybird went into service.

Telephone set

A typical telephone instrument (see Figure 1) includes a number of main blocks (a switchhook, a ringer, a dial, a receiver, a transmitter, and a balancing network), which make it capable of numerous operations. 1) It requests the use of the telephone system when the hand-set is lifted, and signals the system that a call is finished when a caller returns the handset to the cradle. 2) It announces the incoming call by sending audible signals. 3) It sends to the system the telephone

number that is specified by the caller, who rotates a dial or presses number keys. 4) It converts the speech of the caller to electrical signals for transmission through the system and changes received electrical signals to speech. 5) It controls the level of unwanted sounds.

The switchhook interrupts the connection with the central office when the telephone set is idle (the handset is on the cradle) and completes the circuit whenever the handset is lifted off. The ringer is initiated by the system each time when an incoming call is waiting. Alternating current passing through a coil drives a permanent magnet, which makes the attached clapper periodically strike the bell.

The rotary dial is an electric contact that interrupts the circuit periodically sending to the central office a series of current pulses, corresponding to the identification number of the telephone called. When the tone dialing is used, as in touch-tone service, pressing of a number key results in sending a signal of two frequencies to the central office circuit, which identifies it and accordingly sets up the switching for the communication path. The use of tones speeds up the dialing operation and allows sending commands and control information directly to the called location.

The telephone transmitter responds to acoustic frequencies from 250 to 1,000 Hz. It consists of an electrical capacitor adjacent to a diaphragm, so that air-pressure vibrations caused by sound make the membrane produce changes in the value of capacitance of the circuit and, therefore, the variable electric voltage. As a result, a pulsating direct current occurs.

The typical receiver consists of a lightweight diaphragm attached to a permanent magnet associated with a coil of wire. When the alternating current of the telephone signal passes through the winding of the coil, changes are produced in the magnetic forces acting on a permanent magnet. The diaphragm moves in response to these variations, creating an acoustic pressure, more or less exactly reproducing the original sound wave from the distant telephone transmitter.

Sidetone is the sound of the speakers voice heard in his own receiver. To keep the level of this unwanted sound in acceptable range, the balancing network is used.

Special signals informing users on the status of their calls originate from the central office. When a caller lifts off the handset from the cradle the direct current flows through a complete circuit to the central office, which immediately registers the line initiating a call and places a dial tone on it. This tone signals to the subscriber that he may proceed with dialing the number of the called party. If the connection cannot be established, the tone generator in the central office produces one of three possible busy signals. A signal interrupted 60 times per minute means that the called party is busy. A signal interrupted only 30 times per minute indicates that the toll line between the central offices is busy, while a signal with 120 interruptions per minute means that all the intra-office paths are busy.

Telephone network

The telephone networks structure may be defined as an entire plant of existing connections between telephone exchanges. It consists of three broad categories: local, exchange area, and long-haul networks.

The local network (see Figure 2) links telephones in residences and businesses to a central office serving a particular geographical area. The size of the area may vary from 11.5 sq mi (30 km2) in cities to 123.5 sq mi (320 km2) in the country. The telephone lines connecting a subscriber to the central office are called local lines or loops. Central offices are interconnected through the exchange area network, and all of the above are interconnected with toll (long-distance) exchanges. The telephone lines connecting one telephone exchange with another are called trunks in North America and junctions in Europe.

Each telephone is assigned a number indicating its location in the system. The switching network recognizes which telephone initiates the call and which telephone is to receive the call. From this information, it sets up the circuit connection for a signal path. Modern transmission facilities for conveying the electric analog of speech between telephone stations use diverse transmission paths, such as wire or cable circuits and microwave-radio or infrared-optical channels.

Quality of telephone communication

The intelligibility, naturalness, and audibility of transmitted speech are the main requirements for high quality telephone transmission. In technical terms, these requirements mean that: all the harmonic components of the human voice in the frequency range from 300 to 3,400 Hz pass through the communication channel; the loss of a signal during passing the channel does not exceed 30 dB; and the level of noise arising from all types of interference be at least 35 dB lower than the level of the main signals.

The quality of the telephone service is greatly dependent upon the structure of the networks by which subscribers are connected. The number of subscribers making telephone calls at one time is always substantially less than the total amount of subscribers. That is why the number of channels in the commercial telephone system is considerably less than the number of subscribers served by a central office (usually by a factor of seven to ten in a local office and 200250 in toll exchanges). Because of such a design, a connection may be blocked when the telephone traffic is high. The quality of the automatic telephone service can be defined as the percentage of blocked (refused) calls during the hours of the heaviest telephone traffic. To reduce the incidence of channel overload, good planning based on statistical analysis is used.

Another way to improve network quality is to increase the amount of channels that can be carried by a single underlying medium. For example, in 1940, a coaxial cable could carry 600 voice channels. By the early 1950s, this amount increased to 1,860 voice channels and reached the number 13,200 in the 1980s. The microwave radio system experienced similar bandwidth growth, with 2,400 channels in the 1950s increased to 42,000 channels in the 1980s. Fiber optic technology, in 2005, provides even faster progress in this direction with hundreds of thousands of channels per single fiber (without even coming near its total capacity).

Wireless telephone systems

In wireless communication the information is superimposed on a carrier radio signal, which is sent through the air to a receiving location, where the original information is detected and isolated. Cordless, mobile, and cellular telephones perform all functions of the conventional telephone but partially use a radio link instead of wires.

The cordless telephone uses low-power radio transmissions only between the portable handset and its base. The telephone base is wired in a regular way to the telephone line completing the local loop to the central office. An internal antenna in the handset receives the transmission from the base unit over a range up to normally about 950 ft (300 m). The hand-set is powered by a battery, which is automatically recharged when placed in a receptacle in the base unit. When the user dials the number for the outgoing calls, the dial tones are transmitted to the base unit, which sends the tones to the regular telephone line. Cordless phones used the 1.7 MHz frequency range to communicate between the base and the handset when first introduced. However, since then, higher frequency ranges (49 MHz, 900 MHz, 2.4 GHz, and 5.8 GHz) have replaced it

The mobile telephone has no direct hardware connection with the conventional telephone line. It uses a high-power transmitter and an elevated antenna to establish a wireless link with the base station antenna serving a circular area of up to 31 mi (50 km) in radius. The base station receives and transmits on several different frequencies simultaneously, providing clear reliable communications. The control terminal of the base station directs telephone calls to and from the conventional telephone system, just like calls that are carried out entirely over wires. When the user in his moving vehicle lifts the handset of the mobile telephone to place a call, the control terminal automatically selects an available channel. If a channel is found, the user hears the normal dial tone and proceeds as usual.

The cellular telephone concept, first developed and implemented in the United States in the late 1970s, is a

method of providing high quality telephone service to subscribers when they move beyond the boundaries of the home area. This concept suggests dividing a service area into a number of small cells (see Figure 3). Each cell is served by a control terminal, which, like a local central office, can switch, transmit, and receive calls to/from any mobile telephone located in the cell. Each cell transmitter and receiver operates on a designated channel.

There are two essential features of the cellular concept: frequency reuse and cell splitting. Frequency reuse means that the same channel may be used for conversations in cells located far apart enough to keep interference low. This is possible, because each cell uses relatively low-power transmitter covering only limited area, so cells located sufficiently far from each other may use the same frequency. Cell splitting is based on the notion that cell sizes do not have to be fixed. A system with a relatively small number of subscribers uses large cells, which can be divided into smaller ones as demand grows.

The cells are interconnected and controlled by a central Mobile Telecommunications Switching Office (MTSO), which connects the system to the conventional telephone network and keeps track of all call information for billing purposes. During the call, the terminal at the serving cell site examines the signal strength once every few seconds. If the signal level becomes too low, the MTSO looks for a closest to the active user cell site to handle the call. The actual handoff from one cell to the next occurs without getting noticed by a user. Decision to hand off is made by the computer, based on the location analysis, the quality of the signal and potential interference.

The convenience and efficiency of wireless telephone communication is the reason for the impressive growth of this service. Recent market data indicate that there are, as of the beginning of 2006, just under 218 million cellular subscribers in the United States, compared with approximately 4.4 million in 1990, and 90,000 subscribers in 1984. Currently, cellular telephone service is available throughout the United States. The expansion of cellular networks on a global scale is based on employing low altitude low weight satellites. As of 2005, the total number of cell phone subscribers in the world is estimated at 2.14 billion, with about 80% of the worlds population in areas with access to cell phone coverage. The access coverage area is expected to increase to 90% by 2010.

Modern developments in telephony

Along with the television and the telegraph, the telephone is only a part of a large family of complex telecommunication systems. The past several years have seen the digitalization of the networks. Digital technology uses a simple binary code to represent any signal as a sequence of ones and zeros, somewhat similar to the Morse code, which assigns dot-dash combinations to the letters of the alphabet. The smallest unit of information for the digital transmission system is a bit, which is either 1 or 0. Binary codes are very stable against different distortions, and are therefore extremely effective for long-distance transmissions. Conversion to digital form allows for the integration of various modes of information management, opening new possibilities for information display, transmission, processing, and storage. As of 2005, over one-half of the information that passes through telephone lines in the United States ccurs through the use of computers and accessory equipment.

The introduction of the new transmission media (optic fibers) has extended the capabilities and quality of telecommunication services as a whole and telephone service in particular. The fiber optic cable has an almost infinite bandwidth, and is suited especially well for digital transmission. Current tendencies in optical fiber transmission technology include the development of new fiber materials producing a signal loss of no more than 0.001 dB per km as compared to 0.15 dB per km in existing silica-based fibers; the development of effective amplifiers; and the use of the fibers special transmission modes, called solitons, which are so stable that they preserve their shape even after having traveled thousands of miles.

For short distances a cable-free, easily deployed, and cost-effective communication for voice, data, and video is offered by an infrared (IR) optical communication system, employing air as the transmission medium. IR data transmission devices include personal digital assistants (PDAs), which use light-emitting diodes to emit infrared radiation. Infrared signal is another type of electromagnetic emission that is characterized by a considerably higher frequency than microwave. Due to higher frequency, an infrared signal is considerably more directional than a microwave one. The current commercial infrared systems were originally capable of providing reliable telephone links over a range of one half-mile and were ideal for local inter-building communications. However, in the 2000s, such systems are available throughout the United States with the use of wireless service providers.

Voice communications and data communications exist are integrated into a multimedia telecommunication network. Multimedia conferences or one-to-one multimedia calls are set up as easily as voice calls from a desktop device. The same device is used to access FAX and e-mail messaging. Multimedia enables 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.

Voice over internet protocol (VoIP) telephones use a broadband Internet connection or other IP-based (Internet protocol-based) network in order to communicate. Such technology is also called IP telephony, broadband telephony, broadband phone, and other various names.

Conventional networks accommodate multimedia communication services, such as the direct participation of many conferees in an audio/video/data/image work session. Technology, economics, and even environmental factors stimulate peoples readiness to rely on networked contacts. Meeting somebody no longer implies being in the same place together. People separated geographically can still communicate face to face and collaborate productively. The emerging capabilities offered by the unified, intelligent telecommunication network gradually transform the way people interact, work, and learn.

As bandwidth improves in the early years of the twenty-first century (especially with the increased use of fiber optics and advanced wireless technologies), instruments that work as a telephone, plus functions as a computer, office organizer, camera, and television, are becoming commercially popular throughout the world.

KEY TERMS

Attenuation Loss of energy in a signal as it passes through the transmission medium.

Bandwidth The total range of frequencies that can be transmitted through a transmission path; the bigger bandwidth means bigger information carrying capacity of the path. As a rule, transmission path carries multiple channels.

Bel Unit of measurement associated with a tenfold increase in sound energy. Decibel (dB) is one-tenth of a bel, and represents the smallest difference in sound intensity that the trained ear can normally perceive at a frequency of 1,000 Hz. In telephony, 0 dB level is prescribed to a reference point, which is usually the sending end of the transmission line.

Hertz A unit of measurement for frequency, abbreviated Hz. One hertz is one cycle per second.

Optical fiber Glass strands which act as light pipes for light beams created by lasers.

Switching Process whereby the temporary point to point connection between telephone sets is established.

Transmission channel The range of frequencies needed for a transmission of a particular type of signals (for example, voice channel has the frequency range of 4,000 Hz).

Resources

BOOKS

Bigelow, Stephen J. Understanding Telephone Electronics. Boston, MA: Newnes, 2001.

Gray, Charlotte. Reluctant Genius: Alexander Graham Bell and the Passion for Invention. New York: Arcade Publishing, 2006.

Elena V. Ryzhov

Telephone

views updated Jun 08 2018

Telephone

The term telephone (from Greek tele, afar, and phone, sound) in a broad sense means a specific type of telecommunications which permits people to carry direct conversations over almost any distance. The articulate speech is transmitted in a form of either modulated electric current propagating along conductors or radio waves . The apparatus used for converting the verbal sounds into electromagnetic signals and vice versa is called a telephone set and is also commonly referred to as a telephone. Telephone communication is one of the most widespread and expeditious forms of communication. It has proved to be invaluable for an exchange of information in all areas of human life, whether it is business, government, science, public health, personal services, or social contacts. There were about 200,000 telephones in the world in 1887, approximately 30 million in 1928, 118 million in 1958, and more than 330 million in 1975.

The general concept of the telephone as a system involves a number of elements. First comes a telephone apparatus itself. Next, there is a variety of means for conveying the electromagnetic signals over distances (transmission paths). Third, the transmission paths are arranged in multi-leveled structures (networks) in a way that permits to interconnect (switch) any desired telephone sets upon request. And finally, there are signalling facilities for directing the switching operations, alerting the person called, and clearing the circuits upon the completion of the call.

A scientific and technological discipline which studies and develops all of the telephone-system's constituents is called telephony. Many problems in telephony draw on the principles and techniques of the electromagnetic theory, the theory of linear and nonlinear circuits, the probability theory , and the queuing theory.

Invention and historical development of the telephone

Electrical telecommunication originated in the nineteenth century, with the invention of the tele graph—a method of transferring intelligence between distant places through metallic wires in a form of spaced bursts of electricity . A sender, using a special letter code, produced regulated electrical pulses in a circuit. These signals were converted at the receiving end into a pattern of sound clicks, which was decoded by an operator or an automatic device. The next logical step beyond sending of non-articulate messages was the instantaneous transmission of conversation over wires. The intricate and very individual nature of sounds produced by the human vocal cords with the participation of the lips, as well as of the oral and nasal cavities, made this task difficult to accomplish. Articulate (spoken) speech involves not only the elementary sounds and their assembly into syllables, words, and sentences, but also infinite variations in accent, emphasis, intonation, and voice timbre—characteristics of no importance for other types communication.

By no chance, the invention of a way to transmit the human voice electrically was made by a man deeply involved in the study of vocal physiology and the mechanics of speech. A native of Scotland, Alexander Graham Bell (1847-1922) inherited from his father, who was a famous professor of elocution and an author of several textbooks on speech correction, a profound interest in speech and hearing theory, and put his knowledge primarily for the teaching of the deaf. Being interested in electricity, Bell set up a little laboratory and experimented on transmission of sound tones over an electric circuit in an attempt to make a "harmonic telegraph"—a device capable of sending multiple telegraph messages simultaneously over the same wire. On the basis of his experimental observations, Bell gradually came to the conclusion that oscillations of air pressure (sound waves ) could be used to modulate the intensity of electric current in a circuit. Using his knowledge of ear anatomy , Bell attached one end of a metallic organ reed to a thin diaphragm intended to simulate the eardrum. In presence of even weak air-pressure variations caused by the human voice, the diaphragm forced the metallic reed to oscillate in front of the electromagnet and, therefore, to undulate the electric current in the circuit.

Telephones successfully served to the public for almost 23 years before scientists could explain theoretically why the telephone worked. Bell's perception of an "analog" relationship between sound pressure and electromotive force was one of the most fascinating examples of the ingenious intuition in the history of technological discoveries.

Bell first started testing his device for voice transmission in June, 1875, and patented it nine months later. The demonstration of the working apparatus at the Philadelphia Centennial Exposition attracted substantial public interest, which helped to raise some additional monetary funds. On 1 August 1877, with Bell's four patents as a tangible basis for a wide manufacturing of a speaking telephone, the Bell Telephone Company was formed. Bell outlined a general concept of a telephone system as a universal means of voice communication between individuals, at any time, from any location, and without any special skill requirements. This concept might seem obvious today, but it was far in advance of any existing techniques of its time. Giant technological and organizational efforts were required to make Bell's vision of a telephone communication a reality.

The number of existing telephones at that time counted 778, but rapidly growing demand presented the challenge of operating the existing telephone while producing new ones. The first telephone subscribers were directly connected to each other. Under such arrangement, a community of 100 subscribers used 9,900 separate wire connections. For 1,000 subscribers the number of needed wire connections was more than 100 times bigger. The evident impracticality of full-time point-to-point connections stimulated the idea of a central office, or exchange. All the telephone sets in a particular area, instead of being wired permanently to each other, were connected to the same central office, which could establish a temporary link between any two of them on demand. The process of line connecting and disconnecting (switching) was initially performed by trained operators on a switchboard. However, with more and more telephones coming into use the manual switching was becoming increasingly complex. In 1891, the first automatic switching system was introduced.

As local telephone lines emerged and expanded, the idea of the creation and commercial operation of long-distance telephone communication became a necessity. Unfortunately, the already existing telegraph lines were of little use for this purpose. Feeble electric currents used in telephony were rapidly dissipated (attenuated) on their way through iron wires. Compensating for attenuation was one of the main problems of telephony during its first 50 years. Considerable success in reducing the attenuation was achieved by using copper in place of iron wire. The innovation extended the limits of the voice transmission through bare wires to a distance between Boston and Chicago—1180 mi (1,900 km)—in 1893. Later, the effectiveness of wire lines was crucially increased by inserting inductances, or "loading coils," at regular distances in a circuit. For crossing small bodies of water telephone lines were laid in a form of insulated cables instead of bare wires. The invention of radio transmission at the beginning of the twentieth century led to the development of wireless telephone links and accelerated creation of the worldwide telephone system.

Long-haul facilities grew swiftly. In 1900, toll lines totalled 621,000 mi (1 million km) of wire. It took only 25 years to increase this number by a factor of 10. In 1925, almost one-half of the long-distance circuits was cable. The first transatlantic telephone cable (TAT-1) became operational in 1956. Nine years later, the first transatlantic telephone satellite "Earlybird" went into service.


Telephone set

A typical telephone instrument (see Figure 1) includes a number of main blocks (a switchhook, a ringer, a dial, a receiver, a transmitter, and a balancing network), which make it capable of numerous operations. 1) It requests the use of the telephone system when the handset is lifted, and signals the system that a call is finished when a caller returns the handset to the cradle. 2) It announces the incoming call by sending audible signals. 3) It sends to the system the telephone number which is specified by the caller, who rotates a dial or presses number keys. 4) It converts the speech of the caller to electrical signals for transmission through the system and changes received electrical signals to speech. 5) It controls the level of unwanted sounds.

The switchhook interrupts the connection with the central office when the telephone set is idle (the handset is on the cradle) and completes the circuit whenever the handset is lifted off. The ringer is initiated by the system each time when an incoming call is waiting. Alternating current passing through a coil drives a permanent magnet, which makes the attached clapper periodically strike the bell.

The rotary dial is an electric contact that interrupts the circuit periodically sending to the central office a series of current pulses, corresponding to the identification number of the telephone called. When the tone dialing is used, as in touch-tone service, pressing of a number key results in sending a signal of two frequencies to the central office circuit, which identifies it and accordingly sets up the switching for the communication path. The use of tones speeds up the dialing operation and allows sending commands and control information directly to the called location.

The telephone transmitter responds to acoustic frequencies from 250 to 1,000 Hz. It consists of an electrical capacitor adjacent to a diaphragm, so that air-pressure vibrations caused by sound make the membrane produce changes in the value of capacitance of the circuit and, therefore, the variable electric voltage. As a result, a pulsating direct current occurs.

The typical receiver consists of a lightweight diaphragm attached to a permanent magnet associated with a coil of wire. When the alternating current of the telephone signal passes through the winding of the coil, changes are produced in the magnetic forces acting on a permanent magnet. The diaphragm moves in response to these variations, creating an acoustic pressure, more or less exactly reproducing the original sound wave from the distant telephone transmitter.

Sidetone is the sound of the speaker's voice heard in his own receiver. To keep the level of this unwanted sound in acceptable range, the balancing network is used.

Special signals informing users on the status of their calls originate from the central office. When a caller lifts off the handset from the cradle the direct current flows through a complete circuit to the central office, which immediately registers the line initiating a call and places a dial tone on it. This tone signals to the subscriber that he may proceed with dialing the number of the called party. If the connection cannot be established, the tone generator in the central office produces one of three possible busy signals. A signal interrupted 60 times per minute means that the called party is busy. A signal interrupted only 30 times per minute indicates that the toll line between the central offices is busy, while a signal with 120 interruptions per minute means that all the intra-office paths are busy.


Telephone network

The telephone network's structure may be defined as an entire plant of existing connections between telephone exchanges. It consists of three broad categories: local, exchange area, and long-haul networks.

The local network (see Figure 2) links telephones in residences and businesses to a central office serving a particular geographical area. The size of the area may vary from 11.5 sq mi (30 km2) in cities to 123.5 sq mi (320 km2) in the country. The telephone lines connecting a subscriber to the central office are called local lines or loops. Central offices are interconnected through the exchange area network, and all of the above are interconnected with toll (long-distance) exchanges. The telephone lines connecting one telephone exchange with another are called trunks in North America and junctions in Europe .

Each telephone is assigned a number indicating its location in the system. The switching network recognizes which telephone initiates the call and which telephone is to receive the call. From this information, it sets up the circuit connection for a signal path. Modern transmission facilities for conveying the electric analog of speech between telephone stations use diverse transmission paths, such as wire or cable circuits and microwave-radio or infrared-optical channels.


Quality of telephone communication

The intelligibility, naturalness, and audibility of transmitted speech are the main requirements for high quality telephone transmission. In technical terms, these requirements mean that: all the harmonic components of the human voice in the frequency range from 300 to 3,400 Hz pass through the communication channel; the loss of a signal during passing the channel does not exceed 30 dB; and the level of noise arising from all types of interference be at least 35 dB lower than the level of the main signals.

The quality of the telephone service is greatly dependent upon the structure of the networks by which subscribers are connected. The number of subscribers making telephone calls at one time is always substantially less than the total amount of subscribers. That is why the number of channels in the commercial telephone system is considerably less than the number of subscribers served by a central office (usually by a factor of 7-10 in a local office and 200-250 in toll exchanges). Because of such a design, a connection may be blocked when the telephone traffic is high. The quality of the automatic telephone service can be defined as the percentage of blocked (refused) calls during the hours of the heaviest telephone traffic. To reduce the incidence of channel overload, good planning based on statistical analysis is used.

Another way to improve network quality is to increase the amount of channels that can be carried by a single underlying medium. For example, in 1940, a coaxial cable could carry 600 voice channels. By the early 1950s, this amount increased to 1,860 voice channels and reached the number 13,200 in the 1980s. The microwave radio system experienced similar bandwidth growth, with 2,400 channels in the 1950s increased to 42,000 channels in the 1980s. The potential of the fiber optic technology promises even faster progress in this direction.


Wireless telephone systems

In wireless communication the information is superimposed on a carrier radio signal, which is sent through the air to a receiving location, where the original information is detected and isolated. Cordless, mobile, and cellular telephones perform all functions of the conventional telephone but partially use a radio link instead of wires.

The cordless telephone uses low-power radio transmissions only between the portable handset and its base. The telephone base is wired in a regular way to the telephone line completing the local loop to the central office. An internal antenna in the handset receives the transmission from the base unit over a range from 49 to 948.5 ft (15-300 m). The handset is powered by a battery which is automatically recharged when placed in a receptacle in the base unit. When the user dials the number for the outgoing calls, the dial tones are transmitted to the base unit which sends the tones to the regular telephone line.

The mobile telephone has no direct hardware connection with the conventional telephone line. It uses a high-power transmitter and an elevated antenna to establish a wireless link with the base station antenna serving a circular area of up to 31 mi (50 km) in radius. The base station receives and transmits on several different frequencies simultaneously, providing clear reliable communications. The control terminal of the base station directs telephone calls to and from the conventional telephone system, just like calls that are carried out entirely over wires. When the user in his moving vehicle lifts the handset of the mobile telephone to place a call, the control terminal automatically selects an available channel. If a channel is found, the user hears the normal dial tone and proceeds as usual.

The cellular telephone concept, first developed and implemented in the United States in the late 1970s, is a method of providing high quality telephone service to subscribers when they move beyond the boundaries of the home area. This concept suggests dividing a service area into a number of small cells (see Figure 3). Each cell is served by a control terminal, which, like a local central office, can switch, transmit, and receive calls to/from any mobile telephone located in the cell. Each cell transmitter and receiver operates on a designated channel.

There are two essential features of the cellular concept: frequency reuse and cell splitting. Frequency reuse means that the same channel may be used for conversations in cells located far apart enough to keep interference low. This is possible, because each cell uses relatively low-power transmitter covering only limited area, so cells located sufficiently far from each other may use the same frequency. Cell splitting is based on the notion that cell sizes do not have to be fixed. A system with a relatively small number of subscribers uses large cells, which can be divided into smaller ones as demand grows.

The cells are interconnected and controlled by a central Mobile Telecommunications Switching Office (MTSO), which connects the system to the conventional telephone network and keeps track of all call information for billing purposes. During the call, the terminal at the serving cell site examines the signal strength once every few seconds. If the signal level becomes too low, the MTSO looks for a closest to the active user cell site to handle the call. The actual "handoff" from one cell to the next occurs without getting noticed by a user. Decision to hand off is made by the computer, based on the location analysis, the quality of the signal and potential interference.

The convenience and efficiency of wireless telephone communication is the reason for the impressive growth of this service. Recent market data indicate that there are currently more than 100 million cellular subscribers in the United States, comparing with approximately 4.4 million in 1990, and 90,000 subscribers in 1984. Currently, cellular telephone service is available mainly in urban areas. The future expansion of cellular network on a global scale will be based on employing low altitude low weight satellites.


Modern developments in telephony

Along with the television and the telegraph, the telephone is only a part of a large family of complex telecommunication systems. The past few years have seen the digitalization of the networks. Digital technology uses a simple binary code to represent any signal as a sequence of ones and zeros, somewhat similar to the Morse code, which assigns dot-dash combinations to the letters of the alphabet. The smallest unit of information for the digital transmission system is a bit, which is either 1 or 0. Binary codes are very stable against different distortions, and are therefore extremely effective for long-distance transmissions. Conversion to digital form allows for the integration of various modes of information management, opening new possibilities for information display, transmission, processing, and storage.

The introduction of the new transmission media (optic fibers) has extended the capabilities and quality of telecommunication services as a whole and telephone service in particular. The fiber optic cable has an almost infinite bandwidth, and is suited especially well for digital transmission. Current tendencies in optical fiber transmission technology include the development of new fiber materials producing a signal loss of no more than 0.001 dB per km as compared to 0.15 dB per km in existing silica-based fibers; the development of effective amplifiers; and the use of the fiber's special transmission modes, called solitons, which are so stable that they preserve their shape even after having traveled thousands of miles.

For short distances a cable-free, easily deployed, and cost-effective communication for voice, data, and video is offered by an infrared optical communication system, employing air as the transmission medium. Infrared signal is another type of electromagnetic emission which is characterized by a considerably higher frequency than microwave. Due to higher frequency, an infrared signal is considerably more directional than a microwave one. The current commercial infrared systems are capable of providing reliable telephone links over a range of a half-mile and are ideal for local inter-building communications.

Both voice communications and data communications today exist separately. As technologies become more advanced, the best of both worlds will be integrated into a multimedia telecommunication network. Multimedia conferences or one-to-one multimedia calls will be set up as easily as voice calls from a desktop device. The same device will be used to access FAX and e-mail messaging. 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 .

Conventional networks can already accommodate some of the multimedia communication services, such as the direct participation of about 20 conferees in an audio/video/data/image work session. Technology, economics, and even environmental factors stimulate people's readiness to rely on networked contacts. Meeting somebody no longer implies being in the same place together. People separated geographically can still communicate face to face and collaborate productively. The emerging capabilities offered by the unified, intelligent telecommunication network gradually transform the way people interact, work, and learn.


Resources

books

Brooks J. Telephone: The First Hundred Years. Harper & Row, 1976.

Freeman, R.L. Telecommunication System Engineering. New York: Wiley, 1989.


periodicals

Chang, J.J.C., R.A. Miska, and R.A. Shober. "Wireless Systems and Technologies: An Overview." A&T; Technical Journal 72 (July-August 1993).

Udell, J. "Computer Telephony." Byte 19 (July 1994).


Elena V. Ryzhov

KEY TERMS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Attenuation

—Loss of energy in a signal as it passes through the transmission medium.

Bandwidth

—The total range of frequencies that can be transmitted through a transmission path; the bigger bandwidth means bigger information carrying capacity of the path. As a rule, transmission path carries multiple channels.

Bel

—Unit of measurement associated with a tenfold increase in sound energy. Decibel (dB) is one-tenth of a bel, and represents the smallest difference in sound intensity that the trained ear can normally perceive at a frequency of 1,000 Hz. In telephony, 0 dB level is prescribed to a reference point, which is usually the sending end of the transmission line.

Hertz

—A unit of measurement for frequency, abbreviated Hz. One hertz is one cycle per second.

Optical fiber

—Glass strands which act as "light pipes" for light beams created by lasers.

Switching

—Process whereby the temporary point to point connection between telephone sets is established.

Transmission channel

—The range of frequencies needed for a transmission of a particular type of signals (for example, voice channel has the frequency range of 4,000 Hz).

Telephone

views updated May 29 2018

TELEPHONE

Telephone technology allows a person to talk to nearly anyone in any place who has similar equipment. There are substantial ethical questions related to the uses and abuses of the telephone. Among other things, the telephone is a communication system that provides political leaders, pollsters, and social science researchers with some understanding of public attitudes and behaviors. It gives voice to the needs and wishes of citizens as they attempt to make their views known to governments and corporations. Additionally, the telephone is a conduit for the delivery of professional services. As a result of these aspects of what has been an everyday but rapidly changing technology, considerable attention has been devoted to the telephone from ethical, legal, and policy viewpoints.


Historical Development

The term telephone is based on the combination of the Greek words, tele ("distant" or "afar") and phon ("sound" or "voice"); it was first used in France in the 1830s to name a crude acoustic device. By the mid-1800s something akin to a pair of tin cans connected by a taut string was known in the United States as the "lover's telephone." In 1876 Alexander Graham Bell (1847–1922) won a patent for a device that has come to be known as the telephone.

The traditional telephone operates by converting the mechanical energy of sounds carried in the air (the speaker's voice) into electrical impulses for transmission to a receiver. The receiver reverses the process, changing the electrical impulses back into vibrations. Those vibrations are heard as sounds. The original telephones transmitted electrical impulses by wires. Radio and other portions of the electromagnetic spectrum subsequently supplemented or supplanted wires as digital forms replaced analog.

The uses of the telephone have expanded to include multiple forms of data transmission, including fax, photo, and video image formats. Ancillary services have been created and have been widely adopted, including answering machines, caller-ID boxes, and telephone-based security systems. The Internet owes much of its success to the ability of users to go online by means of telephone lines.

In the early period of the telephone myriad uses were explored, including the "broadcasting" of news, opera, weather reports, and religious services. Some contemplated services never materialized: Bell speculated that the telephone might be used to communicate with the deceased. Other services did not materialize because they were outdated before they could deployed: France's national telephone company conducted extensive research in the 1960s to see if the telephone touch-tone pad could be adapted to serve as a home calculator. Yet other services were initially innovative and popular, but then, as technology continued to advance, they were left in the backwater. The fax machine and the French Minitel system are examples of this phenomenon.

Ethical Issues

PRIVACY, SECURITY, AND SURVEILLANCE. Among the early ethical questions was the way the telephone was used to invade privacy in the household and give outsiders access to household members. In particular the telephone allowed outsiders to make social connections with the members of a household, thus violating rigid gender and class roles. Ethical questions relating to various roles in the household, along with the power relationships among those roles, have been exacerbated by the telephone. For example, teenagers and parents come into conflict over appropriate norms for telephone use.

The telephone often leads to disruption of household routines and may allow for social subversion through practical jokes and harassing or obscene phone calls. Women especially have been victimized by such calls, though a surprisingly large number of men have been as well. Although commentators see great net benefits arising from the telephone, they also recognize the moral dilemmas that result from the "distant presence" (a phrase popularized by Kenneth J. Gergen) the telephone allows. The American humorist Mark Twain (1835–1910) was an early acerbic critic of the way the telephone could disrupt trains of thought and ordinary social interaction. In addition, characteristic of early telephone technology was the large proportion of homes that shared local service party lines; this meant that neighbors could listen in to conversations and learn family secrets.

Larger questions of privacy surrounded systematic wiretapping conducted by both licit and illicit organizations. Only a few years after the telephone was invented numerous devices were built to allow not only tapping but also recording of telephone conversations. (Many of these microphone devices also can be used to listen in on in-room conversations.) A wide variety of practices legal and illegal, moral and immoral, could be identified and documented.

Police forces and other governmental agencies sometimes carried out large-scale wiretapping not only in pursuit of wrongdoers but also to monitor those perceived as opposing government policy. In what has become a well-established cycle of innovation, new ways to communicate were followed by new ways to penetrate those forms, followed by steps to enhance privacy. Often a variety of codes would be devised to hinder attempts to collect data and conduct surveillance. The question of the areas in which people had a "reasonable expectation" of privacy was brought to a head when the U.S. Supreme Court decided in Katz v. United States (389 US 347 [1967], docket number 35) that public phone booths were not eligible for systematic tapping by the police.

Although monitoring of workers has been a perennial workplace issue, the telephone gave that issue added impetus because it greatly expanded the ability of managers to tap into the conversations of employees. Telephone companies often have conducted extensive monitoring, sometimes to the point of abuse, when they have used their own technology to monitor employees' behavior and comments. Switchboard operators once were notorious for eavesdropping, though sometimes that allowed them to interrupt the execution of crimes. (Eavesdropping, as opposed to service monitoring or surveillance by officials, is generally prohibited everywhere.) Many companies, including especially telephone companies, have published rulebooks and etiquette guides directed to their employees and managers regarding eavesdropping. While these efforts presumably reduced the problem, they have not been sufficient to extinguish the practice.


TELEMARKETING AND RESEARCH. Telemarketing is the offering of goods or services through sales presentations on the telephone. Because it can be a low-cost, high-profit enterprise, its rapid proliferation has become a source of general annoyance to the targeted public. The Direct Marketing Association and the American Marketing Association instruct their members not to use approaches that might be considered illegal. Moreover, there are numerous laws that regulate telemarketing at the national and local levels. Major moral dilemmas are related to this situation.

On the one hand, there are the claimed rights of businesses to "freedom of commercial speech," which includes the freedom to communicate with potential customers and participation in "fair and efficient markets." (These rights are protected strongly in the United States.) These rights often are carried out with increasingly powerful telephone support technology and database-mining software. On the other hand, individuals have a right to be left alone and not to have information about them collected in secret and without their permission. (These rights are protected strongly in the European Union nations and not as well protected in the United States.) Despite such efforts on both the technological front (such as caller-ID and call blocking) and the legal front (such as the compilation of "do not call lists" and the regulation of times when sales calls may be made), this problem persists.

Social science research and public opinion surveys often are reliant on polling by telephone. Numerous agencies and associations, such as the American Sociological Association (ASA) and American Association for Public Opinion Research (AAPOR) have created codes of conduct for their members, and in some cases governments have stepped in to create regulations in this area. Criminal penalties can be imposed for collecting data improperly by telephone. Many institutional review boards (IRBs) at universities require that researchers demonstrate that they will protect the data and not cause psychological distress, and this applies to telephone surveys as well as to medical experimentation. In more extreme cases, such as at the University of Newcastle in Australia, researchers are required to notify the target population in advance with a written information sheet that warns that telephone contact will be made and includes complete contact information.


UNIVERSAL SERVICE, SOCIAL EQUITY, AND DEMOCRACY. An important ethical component of national and regional policies for telephone technology is equitable distribution. As Claude Fischer (1992) has noted, in its early years the telephone could be considered only a luxury. However, what was an expensive enhancement to lifestyle has in contemporary society become a near necessity for most people.

For much of the twentieth century national telecommunication policies were aimed at subsidizing low-income and rural populations by indirectly taxing (through higher rates) urban and nonpoor telephone subscribers. This was done under the rubrics of social equity and economic development. In fact, in the United States the promise of universal service at an affordable cost was accepted by the government in exchange for the granting of near-monopoly status to the American Telephone and Telegraph Company (AT&T). However, the initial moral clarity of those policies has been obscured as advanced telecommunication technologies have proliferated, especially in the case of the mobile phone.

It is noteworthy that around the world hundreds of millions of subscribers have flocked to new mobile phone services. Those services allow subscribers to leapfrog the long waits and frequently high prices associated with wireline residential services. Moreover, cross-subsidization by ordinary telephone subscribers of low-cost services for schools and hospitals, as is the practice in the United States, means that many people with modest incomes are being penalized for the benefit of institutions in wealthy communities. (Mobile phone subscribers in the United States are exempt from these taxes.)

There can be little doubt that the telephone is an important adjunct to democracy on the level of political expression and as a bulwark against excessive governmental power. At the same time, terrorists and those seeking radical regime change can use the telephone to further their aims. In light of this situation many governments monitor telephone conversations and in some cases limit or prohibit mobile phone services. As instances, North Korea forbids civilian mobile phones on security grounds and Colombia's mobile phone networks were selectively turned off by the government in an effort to detect the location of cell phone-toting drug lord Pablo Escobar.


Public Use of Mobile Telephones

Each major advance in telephone technology has been accompanied by some social disruption. In most cases the disruptions have been transient. With the advent of the mobile telephone, however, high levels of conflict continue. These conflicts often may be understood in terms of what is known in psychology as the actor-observer paradox. The person who wishes to use the mobile phone (the actor) does so because he or she has good cause and with the expectation that others will understand and accept that necessity. However, the people around the user (the observers) view the situation differently. They feel that the mobile phone user is being selfish and self-indulgent and is failing to respect the conventions of polite society. The public use of mobile phones is likely to remain a source of normative conflict because the sources of irritation are not merely conventional but seem to go to the core of human cognitive processes. The result could be that as mobile phone users pursue the private pleasures of conversation there will be a reduction in civility and personal engagement in public places. Perhaps no better illustration of this process is the havoc wrought by drivers who are preoccupied by their mobile telephone conversations.

Provision of Professional Services

The ease and flexibility of telephone use have led many professional organizations to develop codes of conduct that allow their members to use the telephone, under appropriate conditions, to serve clients. This is the case with the many national and worldwide associations of lawyers, for instance. However, the potential for abuse also has led many organizations, such as the Legal Profession Advisory Council, to remind their members that whereas the telephone can be used to discuss and provide confidential information, both the professional and the client have to agree to this in advance. It further recommends that a scrambling device or other encryption technology be used. All advertisements for lawyers should bear the attorney's phone number prominently.

The question of recording telephone conversations is fraught with ethical and moral questions. In one instance (LEO 1738, 48/10 Va Lawyer Reg 23, April 13, 2000) the Virginia state bar association reexamined the subject of taping telephone conversations. That association concluded that all forms of wiretapping, along with one-party-consent recording of telephone conversations by lawyers, are prohibited. Although many people disagreed with that conclusion, it did arrive at the formulation that because wiretapping involves "deceit," the practice must be forbidden. This raises problems when, for instance, testers try to prove housing discrimination by pretending to be people other than who they are. The rules even make it unethical for an attorney who receives an obscene or threatening phone call to record it.

The American Medical Society counsels physicians that telephone advising and referral services should be used only to complement face-to-face interaction and that both the physicians and the clients should be well aware of the limitations of the medium. They urge that no physician make a clinical diagnosis or prescribe medications by telephone and at the same time be certain to elicit all-important information over the phone. They also should avoid generating large telephone bills that their patients or others have to pay.


Counseling by Telephone

Telecounseling has been defined as using the telephone for synchronous but distant interaction between counselors and clients for one-to-one conferencing. Obviously, such interactions are fraught with ethical issues. In response, the National Board for Certified Counselors (NBCC) says that its members should base the use of telecounseling on the needs and convenience of the client. The NBCC further stresses that telecounseling should only be a supplement to face-to-face counseling.

Confidentiality is an important consideration because it may be difficult to know precisely with whom one is speaking when one receives a telephone call. Thus, the American Psychological Association's guidelines warn counselors about privacy and confidentiality issues. The International Chiropractors Association of California has in its code of ethics the statement that its members "shall not discuss any patient information over the telephone with anyone without the patient's consent, preferably in writing." The International Association of Coaches instructs coaches to take precautions to ensure the confidentiality of telephone communications with clients.

In areas in which telephone counseling would be inappropriate professional codes of conduct underscore the importance of avoiding abuse. Thus, the Michigan Speech and Hearing Association urges that the telephone not be used for "diagnosis, treatment or re-evaluation of individual language, speech or hearing disorders." Medical and legal associations have guidelines that also are meant to avoid problems and underscore to their members that using the telephone may be construed as entering into a relationship with a client, with all the demands such a relationship entails.

More Complications Ahead

Because the telephone can obscure many of the ways in which people recognize each other or understand an evolving situation and can transcend distance, it opens new opportunities for ethically questionable or unethical behavior. In addition, as a result of the simplicity and power of the telephone, it has become a vital component of modern life. A variety of codes of conduct, laws, and corporate and governmental regulations have been developed to address these problems. However, these attempts have had incomplete success. Even as recent events are grappled with through norms and regulations, new telephone-based technologies that allow even more forms of use and abuse are complicating efforts to control telephone behaviors through technological countermeasures and moral and legal sanctions.


JAMES E. KATZ

SEE ALSO Communication Ethics;Communication Systems;Monitoring and Surveillance;Networks;Privacy;Security.

BIBLIOGRAPHY

Fischer, Claude. (1992). America Calling: A Social History of the Telephone to 1940. Berkeley: University of California Press. A profound analysis of technology's influence on social relationships and community. Fischer explores the integration of the telephone into society, thereby uncovering and illuminating important interplays between the communication processes and social structures.

Katz, James. (1999). Connections: Social and Cultural Studies of the Telephone in American Life. New Brunswick, NJ: Transaction. A detailed, empirical study of the ways telephone are used in ordinary (and extraordinary) circumstances. Explores norms and behaviors revolving around the telephone via methods including national surveys, interviews, and ethnographic observation.

Pool, Ithiel de Sola, ed. (1977). The Social Impact of the Telephone. Cambridge, MA: MIT Press. This path-breaking collection of historical and cultural studies on the telephone has become a classic and still has much to offer. It grew out of AT&T-sponsored lectures at MIT to celebrate the Centennial of the telephone's invention.

Ronnell, Avital (1989). The Telephone Book: Technology-Schizophrenia-Electric Speech. Lincoln: University of Nebraska Press. An eccentric but probing look at the deeper processes involved in the social and phenomenonological construction of the telephone. The volume is a wry postmodern achievement in both form and content.

Telephone

views updated May 23 2018

Telephone

Sections within this essay:

Background
Federal Regulation of Telephone Companies and Telephone Services
The Communications Act of 1934
Recent Amendments to the Communications Act of 1934

State Regulation of Telephone Companies and Services
AdditionalResources
Organizations
Federal Communications Commission
Public Utility Commission of Texas

A "telephone" is an apparatus for the transmission of human speech or other sounds over distances greater than the limits of ordinary human audibility. The business of transmitting information by telephone is quasi-public in character. The law treats telephone companies both as common carriers of information and as public utilities. As such, telephone companies are regulated by the Federal Communications Commission (FCC) at the federal level and by public utility commissions at the state level. Telephone systems may generally be owned and operated by a partnership, an individual, or a corporation.

Background

Invented by Alexander Graham Bell in 1876, the original telephone was described as a mere improvement upon the magnetic telegraph, which sent data as fast as electrons could move along wires. Unlike telegraph companies, however, telephone companies do not receive, transmit, or deliver messages in the ordinary sense of these terms. Instead, telephone companies furnish customers with networks, facilities, and devices through which conversations can take place over long distances.

The telephone-services sector began to develop in the late nineteenth century when several patents registered by Bell began to expire, while independent local telephone companies began to proliferate in major cities. At first, telephone service in the United States was predominantly local because satisfactory technology for transmitting long-distance calls did not exist. However, American telephony witnessed an explosion in technological innovations during the early twentieth century, including the invention of a "vacuum tube," which allowed phone conversations to be transmitted over distances of several miles.

The Bell telephone companies—under the parentage of the American Telephone and Telegraph Company (AT&T)—patented and deployed this technology across state lines. But they typically refused to allow independent telephone companies to interconnect with their long-distance service. As a result of this handicap and the intense price competition with the Bell companies, many independent telephone service providers chose to sell their companies to AT&T. By the advent of the 1930s, AT&T controlled approximately 80% of local exchange lines in the United States. These practices placed AT&T in the cross hairs of antitrust authorities, who convinced Congress of the need for regulation in this area.

Federal Regulation of Telephone Companies and Telephone Services

The Communications Act of 1934

After conducting a series of hearings on AT&T's growing dominance over American telephoning, Congress determined that AT&T and its competitors were public service corporations whose facilities and instruments were devoted to public use, which made them subject to two kinds of legislative control, state and federal. States may regulate the transmission of telephone communications wholly within state boundaries, Congress said, so long as such intrastate communications do not substantially affect interstate commerce. Once a telephone communication crosses state boundaries or substantially affects commerce in more than one state, Congress observed, the Commerce Clause of the U.S. Constitution gives only federal authorities the power to regulate such interstate communications. U.S.C.A.Const.Art. I, section 8, clause 3. Congress formalized these findings in the Communications Act of 1934.

The Communications Act of 1934 establishes a dual system of state and federal regulation for telecommunications services. 47 USCA sections 151 et seq. The act grants the FCC broad authority, but also clearly delineates a strict separation between interstate and intrastate jurisdiction, and denies the FCC authority over most intrastate communications. The act also establishes the Federal-State Communications Joint Board to hear disputes that involve questions concerning both interstate and intrastate telephone transmissions, and any other telecommunications dispute deemed to involve a mixture of state and federal concerns.

In determining whether the FCC has jurisdiction to regulate a particular telephone service provider, the focus is on the nature of the service at issue, since the FCC may regulate telephone services only to the extent of their interstate use. However, purely intrastate telephone facilities and services that are used to complete even a single interstate call can fall under FCC jurisdiction depending on the nature of that phone call. Thus, the FCC has authority to regulate use of an intrastate call made on a Wide Area Telecommunications Service (WATS) when that service is used as part of an interstate communications network. National Association of Regulatory Utility Commissioners v. F.C.C., 746 F.2d 1492 (D.C. Cir. 1984). Similarly, where a telephone company has all of its facilities within one state and solely engages in intrastate telephone communication except for its physical connection with carriers doing business in other states, it is still subject to federal regulation under the Communications Act as a connecting carrier. At the same time, the FCC does not have authority to order connecting carriers to continue interconnection agreements with interstate telecommunication service providers. Accordingly, connecting carriers are free to remove their interconnection with any interstate carrier, and thereby remove themselves completely from jurisdiction of the FCC.

Recent Amendments to the Communications Act of 1934

Telephone companies that are subject to federal jurisdiction under the Communications Act are also subject to any other applicable laws, regulations, or rules enacted by Congress or promulgated by a federal agency. On three occasions during the 1990s Congress amended the Communications Act of 1934, updating its provisions in light of technological developments and market conditions. In 1991 Congress passed the Telephone Consumer Protection Act (TCPA) to give Americans greater freedom at home from unsolicited commercial advertisements. 47 U.S.C.A. section 227. The TCPA generally imposes restrictions on unsolicited advertisements made through automatic telephone dialing systems, artificial or prerecorded voice messages, and telephone facsimile machines.

The FCC began fleshing out these restrictions when it promulgated a regulation requiring telemarketers to create do-not-call lists for consumers who ask not to receive further solicitation. The FCC also limited the hours during which telemarketers may call a consumer's residence (not prior to 8 a.m. or after 9 p.m.). Additionally, the FCC issued a rule flatly prohibiting the transmission of unsolicited advertisements via telephone facsimile machines. Finally, the FCC published a regulation requiring all artificial or prerecorded messages delivered by an auto-dialer to clearly identify the caller at the beginning of the message.

In 1992 Congress again amended the Communications Act of 1934, when it passed the Telephone Disclosure and Dispute Resolution Act (TDDRA). 15 U.S.C.A. section 5701. The TDDRA regulates how telephone carriers may offer pay-per-call services (e.g., 900 numbers), and prohibits unfair and deceptive practices undertaken by telephone carriers in connection with pay-per-call services, including mis-leading and fraudulent billing and collection practices.

Specifically, the TDDRA provides that any interstate telephone service, other than a telephone company directory assistance service, that charges consumers for information or entertainment must be provided through a 900 number unless it is offered under what is termed a "pre-subscription or comparable arrangement." That pre-subscription or comparable arrangement may be a preexisting contract by which the caller has "subscribed" to the information or entertainment service. The arrangement may also be made through the caller's authorization to bill an information or entertainment service call to a prepaid account or to a credit, debit, charge, or calling card. Telephone companies may not disconnect local or long-distance telephone service for failure to pay 900 number charges, and must offer consumers the option of blocking access to 900 number services if technically feasible. Telephone companies that bill consumers for pay-per-call and pre-subscribed information or entertainment services must show those charges in a portion of the bill that is separate from local and long-distance charges.

Despite increased regulation at the federal level, the telephone service market in the United States remained largely monopolistic for most of the twentieth century, continuing to be dominated by a few small companies in each region of the country. Congress attempted to increase competition by passing the Telecommunications Act 1996 (the "1996 Act"), which allows multiple "local exchange carriers" (LECs) to compete for customers. 1996 Pub.L. No. 104-104. The 1996 Act amends the 1934 Act by distinguishing between incumbent LECs (ILECs) and competing LECs (CLECs). ILECs are existing telephone service providers that have established a telecommunications network in a given market. CLECs are telephone service providers that seek access to an ILEC's market.

One way in which the 1996 Act attempts to improve competition is through "interconnection agreements" and "reciprocal compensation agreements." 47 U.S.C.A. section 251. "Interconnection agreements" require ILECs to make their telecommunications networks available (via purchase or lease ) to CLECs so that a phone call initiated by the customer of an ILEC may be connected to the customer of a CLEC, and vice versa. "Reciprocal compensation agreements" require the carrier for the customer who initiates a phone call to share some of its revenues from that call with the carrier of the customer who receives the call (the telecommunications industry describes the LEC of the customer who receives the call as the one that "terminates" the call and not the one that "receives" it). These requirements were challenged and upheld in federal court on two separate appeals, and are now under consideration by the U.S. Supreme Court. Illinois Bell Telephone Co. v. Worldcom Technologies, Inc., 179 F.3d 566 (7th Cir. 1999); Bell Atlantic Maryland, Inc. v. MCI WorldCom, Inc., 240 F.3d 279 (4th Cir. 2001). In a related case, the U.S. Supreme Court upheld FCC rules that require ILECs to lease their networks to competitors at heavily discounted rates. Verizon Communications, Inc. v. F.C.C., ―U.S.―, ― S.Ct. ―, ― L.Ed.2d ―, 2002 WL 970643 (U.S., May 13, 2002).

State Regulation of Telephone Companies and Services

State law regulates intrastate telephone services that do not substantially affect interstate commerce. It is the policy of each state to protect the public interest in having adequate and efficient telecommunications services available to every state resident at a just, fair, and reasonable rate. To carry out this policy and to regulate rates, operations, and services, state public utility commissions (PUCs) have the general power to regulate and supervise the business of each public utility within its jurisdiction and to do anything that is necessary and convenient in the exercise of its power. For example, state PUCs are typically given exclusive jurisdiction to determine whether a telephone utility should be permitted to close a business office in a given community.

PUCs are also commonly charged with the exclusive responsibility to enhance competition by adjusting regulation to match the degree of competition in the marketplace so that costs associated with running a utility do not deter new telephone service providers from entering the market. State PUCs must ensure that telephone rates are not unreasonably preferential, prejudicial, predatory, or discriminatory and are applied equitably and consistently throughout its jurisdiction. Additionally, PUCs may supplement federal law by enacting their own rules and regulations governing pay-per-call services, unsolicited advertisements, automatic dial announcing devices, or any other feature of local telephone service that might adversely affect consumers.

An individual, partnership, or corporation may not normally offer local telephone service without complying with PUC rules and regulations. In most states, the PUC requires that before a telephone company may provide local service each company must obtain (1) a certificate of convenience and necessity; (2) a certificate of operating authority; or (3) a service provider certificate of operating authority. PUCs may revoke or amend a certificate of convenience and necessity, a certificate of operating authority, or a service provider certificate of operating authority after notice and hearing if it finds that the certificate holder has never provided or is no longer providing service in all or any part of the certificated area. PUCs may also require one or more public utilities to provide service in an area affected by the revocation or amendment of a certificate held by a public utility.

Organized for public purposes to more efficiently serve its customers, telephone companies are usually granted special privileges and powers in addition to those that they possess as private corporations. For example, telephone corporations, telephone cooperatives, and foreign telephone companies are often given the power of eminent domain, which gives these entities a right-of-way to erect, construct, and maintain necessary stations, plants, equipment, or lines upon, through, or over private land. The delegation of the state's power of eminent domain has been held valid because of the public good derived from installing telecommunications systems on private property.

On the other hand, local telephone companies have no absolute right to use city streets to erect telephone poles or configure their facilities and networks. Instead, telephone companies must first obtain consent from the municipal authorities of the city in which they are seeking to provide telephone service. This consent is commonly manifested by the grant of a franchise from the governing municipal authority, and PUCs should not unreasonably restrict the rights and powers of municipalities in granting or refusing a telephone company the right to use city streets. However, cities, towns, and villages have no right to deny telephone companies all use of their streets, and when a municipal corporation unlawfully rejects a telephone company's application to erect poles and string wires along certain public streets, it abandons the right to prescribe the streets on which the line will be constructed.

AdditionalResources

West's Encyclopedia of American Law St. Paul: West Group, 1998

American Jurisprudence St. Paul: West Group, 1998

Organizations

Federal Communications Commission

445 12th Street S.W.
Washington, DC 20554 USA
Phone: (888) 225-5322
Fax: (202) 835-5322
E-Mail: [email protected]
URL: http://www.fcc.gov
Primary Contact: Michael K. Powell, Chairman

Public Utility Commission of Texas

1701 N. Congress Avenue
Austin, TX 78711-3326 USA
Phone: (512) 936-7000
E-Mail: [email protected]
URL: http://www.puc.state.tx.us/about/index.cfm
Primary Contact: Lane Lanford, Executive Director

Telephone

views updated May 11 2018

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

views updated Jun 08 2018

Telephone

The telephone is a device for conducting spoken conversations across any distance beyond the range of the unaided human ear or the unamplified human voice. It works by transferring the atmospheric vibrations of human speech into a solid body, and by converting those vibrations into electrical impulses sent through a conducting medium—originally metal wires, but now optical fibers and electromagnetic microwaves as well. The word is a compound of two Greek words, " tele " ("far") and " phone " ("sound"), and the instrument is the most widely-used of all telecommunications appliances, with hundreds of millions of telephones in use all over the world. On any given business day, approximately two billion calls are placed, just in the United States. The telephone is also the archetypal electronic "medium," in the sense of the word intended by Marshall McLuhan—an "extension of man"—but its social impact is grossly understudied in favor of the more readily observable "bully blow" of the television. Telephones are small and unobtrusive and their impact on our visible environment (except for the poles and wires) has not transformed our relationship to it.

Notwithstanding a host of rival claimants, the traditional account of the telephone's invention by the Scottish-born Alexander Graham Bell (1847-1922) remains substantially the correct one. While the word "telephone" itself had been used to describe a device similar to a children's string telephone as long ago as the seventeenth century, and although the general concepts on which the invention was based had been known for several decades, it was certainly Bell who experienced the sudden flash of insight which he immediately translated into a working model.

Bell and his assistant Thomas Watson had been trying to develop not a telephone, but something Bell called a "harmonic telegraph," by which he hoped to expand the bottleneck throttling communications traffic and permit the transmission of more than one telegraph message over a single wire at the same time. Bell's ideas involved a series of vibrating metal reeds (like those used in wind instruments). Of course, once he had developed that technology, his goal was, in fact, to discover a way to transmit all the sounds of the human voice via his "harmonic telegraph." On June 2, 1875, Bell and Watson were working at opposite ends of a line and Bell heard the distinct sound of a plucked reed coming through the line. He ran to the next room and shouted to his assistant, "Watson! What did you do then? Don't change anything!" From that moment, it took only an hour or so more of plucking the reeds and listening to the sounds they made before Bell was able to give Watson instructions on making the first "Bell telephone," which was capable of transmitting only the sounds of the human voice, not words. Bell and Watson worked through the summer of 1875, and in September, Bell began to write the specifications for his basic patent, which was issued on March 7, 1876 (#174,465). It is, to date, the most valuable patent ever issued. (The famous "Mr. Watson, come here! I want you!" was spoken after the first patent was issued, when Bell and Watson were working on perfecting their transmitter.) Ultimately victorious, Bell had to defend his patent in over 600 separate lawsuits.

The Bell Telephone Company, first of its kind, was founded on July 9, 1877. That same July, Bell married Mabel Hubbard and sailed to England to introduce his telephone there. Well before 1900, Thomas Watson, Thomas Edison, Emil Berliner, and others had worked with Bell's patented technology to produce what would be recognized as a telephone in the late 1990s. The telephone has consisted of the same basic components: a power source, switch hook, dialer, ringer, transmitter, and receiver.

The social impact of the telephone has been literally incalculable. Although the telegraph, patented by the painter Samuel B. Morse in 1840, enjoys pride of place as the first electric instrument to extend and greatly speed human communication, it never became a ubiquitous home appliance like the telephone—it was too complicated to use, and required too much special knowledge (codes, key technique). All a person needs to know in order to use a telephone is how to talk and to listen; it is not necessary to be literate or to have more than a minimal mechanical aptitude. It is, moreover, next to impossible to gossip using a telegraph. Like a religion, telegraphy has its privileged class, the operators, and gossip passes most freely between equals, without going through an intermediary. Because the telephone enables two people to exchange gossip directly, though they may be on opposite sides of the Earth, the telephone has, more than any other invention, produced what Marshall McLuhan called "the global village."

The telephone has changed war and business and the whole gamut of public activities, as well, but it has not transformed them out of recognition, the way it has altered the fundamental relationship of one individual to another and of one individual to society. Warfare is altered by the invention of a new weapon, from the metal sword to the atomic bomb; business is altered by intellectual inventions like double entry book-keeping or speculation or advertising or market capitalism. Public life has changed with the emergence of new institutions—the law, the "Republic," democracy, dictatorship—and is now being replaced by the television camera.

But the telephone began the seismic shift in sensibility described by Martin Pawley in his book The Private Future : "Western societies are collapsing not from an assault on their most cherished values, but from a voluntary, almost enthusiastic abandonment of them by people who are learning to lead private lives of an unprecedented completeness with the aid of the momentum of a technology which is evolving more and more into a pattern of socially atomizing appliances." The telephone, which has been traditionally promoted as a means of bringing people together, of connecting them, is in fact the archetype of Pawley's "socially atomizing appliance." The filmmaker Bill Forsyth gives a perfect example of this in his film, Local Hero. The character played by Peter Riegert wants to invite to dinner a girl standing less than 20 feet away from him on the other side of a glass partition—so he dials her extension. That is "the Private Future" in action.

Cordless phones, answering machines, cellular phones, "call waiting," phones in automobiles, headset phones which free up both hands—all these seem likely to increase our dissociation from the here and now, and to hasten our withdrawal from the public sphere into "private lives of an unprecedented completeness." The dangers inherent in the disappearance of any meaningful public life should be obvious. On the most primitive level, consider the person driving a big shiny suburban wagon, about to negotiate a tricky left turn through a busy intersection while they chat on the telephone with a friend. This person has the illusion of being in two places at once—with the friend and in traffic—but is in fact nowhere at all. The friendship, however, is not in physical danger—the other vehicles approaching that intersection, along with their passengers, are in the gravest peril. By the end of the 1990s legislation restricting the use of telephones in automobiles in the United States began to pass in several states. The whole concept of interdependence, of civic responsibility, is losing its force. The huge juggernaut of communications technology which was launched when Alexander Graham Bell burst in on Thomas Watson and shouted "Don't change anything!" has changed everything. Whether for the better or the worse depends on the relative importance you ascribe to the social contract.

—Gerald Carpenter

Further Reading:

Casson, Herbert Newton. The History of the Telephone. Chicago, A.C. McClurg, 1910.

Coe, Lewis. The Telephone and Its Several Inventors: A History. Jefferson, North Carolina, McFarland, 1995.

Fischer, Claude S. America Calling: A Social History of the Telephone to 1940. Berkeley and Los Angeles, University of California Press, 1992.

Harlow, Alvin F. Old Wires and New Waves: The History of the Telegraph, Telephone, and Wireless. New York, D. Appleton-Century, 1936.

McLuhan, Marshall. Understanding Media: The Extensions of Man. New York, McGraw-Hill, 1964.

Pawley, Martin. The Private Future: Causes and Consequences of Community Collapse in the West. London, Thames and Hudson, 1973.

Prescott, George B. Bell's Electric Speaking Telephone: Its Invention, Construction, Application, Modification, and History. 1884. Reprint, New York, Arno Press, 1972.

Stehman, Jonas Warren. The Financial History of the American Telephone and Telegraph Company. Boston, Houghton Mifflin, 1925.

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

Telephone

views updated May 14 2018

TELEPHONE.

BIBLIOGRAPHY

What the railway represented to the nineteenth century, the telephone arguably represented to the early twentieth: a symbol of progress, a means of conquering distance, an instrument of social integration. From its first appearance in Europe at the end of the nineteenth century, the telephone excited amazement on the part of contemporaries, who saw in it one of the most charismatic technologies of modern life. Before it could fulfill its promise, however, several technical problems had to be resolved. Early telephone exchanges were chaotic spaces, featuring a spaghetti-like tangle of wires and a primitive division of labor. A single call could pass through the hands of five different operators, usually young boys who shouted to each other and ran from switchboard to switchboard to make connections. The result was chronic bad connections and delays. By the early 1900s, however, this arrangement had given way to the configuration that defined the telephone exchange throughout the first half of the twentieth century, until the advent of automation: sophisticated "multiple" switchboards operated exclusively by women. Together, the new switchboard technology and its female operators ushered in the age of mass telephone use. Thirty years after the first exchanges (for fifty users) had opened in the early 1880s, modern multiple connection systems serving ten thousand subscribers were in wide use in Europe's capitals.

The development of the exchange, which led to the creation of networks spanning the Continent and beyond, turned the telephone into a revolutionary instrument. Transformed from a service employed primarily by the business class into a system serving a mass public, it completely reordered the scale of social communication and interaction, breaking down barriers of distance, both geographic and social. The telephone made possible new kinds of everyday communication and relations and became indispensable to the evolution of a new financial order. This expanded space of social interaction was reflected in that eminently modern artifact, the phone directory, in which the German industrialist Walther Rathenau saw an image of modern society's ever-growing complexity.

The integration of the telephone into national life varied across Europe. It occurred fastest in Germany, where 1.3 million phones were in use by 1914, and over 2.5 billion separate phone calls were being made annually. In Britain, the number was about half that in Germany, with France and Italy lagging still further behind. Everywhere it spread, the telephone contributed both to the growth of urban civilization and to the increasing linkages between city and province. The telephone facilitated a tremendous process of centralization. It brought about a new concentration of offices in urban areas and made a decisive contribution to the organized bureaucracy that was one of the hallmarks of the twentieth century.

As the European landscape was crisscrossed by miles of wire, contemporaries hailed telephony as an invention that would, by multiplying contacts, promote peace and stability in world affairs. Unlike previous communications networks, the telephone system, by virtue of the fact that it transmitted the human voice, permitted an unprecedented degree of intimacy and immediacy in social relations. It became possible to imagine the telephone system as almost coextensive with society itself, a national nervous system that helped coordinate the functions of the larger social body.

But just as it inspired images of instantaneous communication, order, and efficiency, so too the telephone created new possibilities of breakdown and overload. The volume and speed of electronic communication tended to eliminate time for reflection and consultation. This would become tragically evident with the frantic exchange of phone calls that marked the July crisis, which imposed its own momentum and logic on the events leading up to the outbreak of World War I. The field telephone played an instrumental role in organizing the rationalized slaughter that followed. And whereas the development of financial systems in their modern form would have been unthinkable without the telephone, so too these systems proved highly vulnerable to the new forms of panic selling, and the financial crises these could engender, made possible by this means of communication. Thus the telephone was linked both with new possibilities for connectivity but also new possibilities for social instability.

Many of these possibilities came to be located in the figure of the female operator. By the turn of the century switchboard work had become an exclusively female occupation, and by the mid-1920s the German state employed sixty-five thousand women at its switchboards. These new white-collar employees became the human face on a technology that despite its everydayness remained beyond the comprehension of most users. Marcel Proust referred to them as "priestesses of the Invisible," who bring us the sound of "distance overcome." These women shared the mystique of the telephone but also its uncanniness. For just as the railway had generated an iconography of technology out of control, so too the telephone revealed a similarly dark side. Writing of his childhood in Berlin, Walter Benjamin described the telephone as "an infernal machine" "shrilling from the darkness"; for the young boy, the corner of the hallway where it stood was a site emanating terror. Benjamin recalled the change his father underwent when using this instrument. Normally a courteous man, the telephone brought out an irritable quality in his father, who engaged in repeated altercations with operators.

Equally troubling from the point of view of social conservatives was the fact that the telephone permitted new forms of unsupervised contacts between male callers and operators. By bursting the boundaries of traditional forms of communication, the telephone created social spaces in which new forms of communication could occur. The operator became an object of romantic longing and erotic fantasy, a development that caused serious misgivings among traditionalists. A more serious threat to the social order was posed by worker militancy at the exchange. The centralization facilitated by the telephone made society highly vulnerable to the disabling effects of a strike at the big urban exchanges. One strike staged by German operators in the midst of the revolutionary turmoil of 1919 cut central state authorities off from the rest of the nation and was only ended with the help of a loyal military telegraph unit.

In response to such threats, authorities maintained an ever-watchful eye over operators. Telephone exchanges became minutely regulated, thoroughly rationalized spaces, and the degree of supervision exercised over these women reached a level unparalleled in any other occupation. Although such measures helped maintain discipline among the personnel, they also further intensified the already considerable demands of this job and heightened workplace discontent. The solution to these problems was eventually found in automation. The first rotary dial telephone was developed in 1923 by the Frenchman Antoine Barnay, and by the late 1920s direct dial systems were entering into usage in most European countries. Not until the 1960s, however, was telephony fully automated and, later, given wireless freedom.

See alsoComputer Revolution; Television.

BIBLIOGRAPHY

Benjamin, Walter. "A Berlin Chronicle." In his Reflections: Essays, Aphorisms, Autobiographical Writing. New York, 1986.

Bertho, Catherine. Telegraphes et Telephones de Valmy au Microprocesseur. Paris, 1981.

Brooks, John. Telephone: The First Hundred Years. New York, 1976.

de Sola Pool, Ithiel, ed. The Social Impact of the Telephone. Cambridge, Mass., 1977.

Casson, Herbert N. The History of the Telephone. New York, 1910.

Gold, Helmut, and Annette Koch, eds. Das Fräulein vom Amt. Munich, 1993.

Gumbrecht, Hans Ulrich. In 1926: Living at the Edge of Time. Cambridge, Mass., 1997.

Kern, Stephen. The Culture of Time and Space, 1880–1918. Cambridge, Mass., 1983.

Nienhaus, Ursula. Vater Staat und seine Gehilfinnen: Die Politik mit der Frauenarbeit bei der deutschen Post (1864–1945). Frankfurt and New York, 1995.

Thomas, Frank. "The Politics of Growth: The German Telephone System." In The Development of Large Technical Systems, edited by Renate Mayntz and Thomas P. Hughes, 179–214. Frankfurt and Boulder, Colo., 1988.

Webb, Herbert Laws. The Development of the Telephone in Europe. London, 1911.

Andreas Killen

Telephone

views updated May 23 2018

Telephone

A telephone is a device for carrying sounds over long distances. The word is a combination of the Greek words tele, meaning distant, and phone, meaning sound. Telephones work by sending sound either as electric current through wires or as radio waves through space. The invention of the telephone in the latter half of the nineteenth century forever changed the way Americans live and conduct business.

Invention

Electrical telecommunication began early in the nineteenth century with the invention of the telegraph in 1837 by Samuel F. B. Morse (1791–1872). Telegraph systems sent electric pulses through wires. The telegraph allowed people to communicate long distances using a code that assigned letters and numbers to different combinations of short and long electric pulses.

Telephones work by transforming the human voice into electric currents sent through metallic wires. The first working telephone was invented by a German, Johann Philipp Reis (1834–1874), in 1863. Reis devised the telephone for the scientific purpose of demonstrating the nature of sound. He never developed a commercial use for the instrument.

In America, two people applied for patents for telephone inventions on the same day, February 14, 1876. Alexander Graham Bell (1847–1922) filed his application with the U.S. Patent Office just two hours before Elisha Gray (1835–1901) filed his. Because Bell was first, he acquired important legal rights for the invention, so history remembers him as the man who invented the telephone.

Bell was a Scottish immigrant who was a teacher for the deaf. His interest in speech and hearing theory moved him to experiment with inventing a telephone. Bell discovered that variations in air pressure could change the intensity of the electric current in an electrical circuit. In his first systems, air pressure made a thin disk called a diaphragm vibrate, causing a metallic organ reed to vibrate near an electromagnet, which made electricity in a circuit change strength with the vibrations. Bell began testing his system in June 1875 before applying for patents to protect his invention in February 1876.

Local service

By August 1877, Bell had received four patents for his telephone technology. With them he formed the Bell Telephone Company. The company offered telephone service to subscribers by connecting them directly with telephone lines. With such a system, a community of one hundred subscribers needed ninety-nine hundred separate wire connections to link each subscriber to each of the others.

The development of central switching offices reduced the number of lines needed in a local telephone system. Instead of connecting every subscriber to every other subscriber, each subscriber was connected only to a central office. Human operators in the central office connected individual lines when one person called another. The invention of automatic switching technology in 1891 eventually eliminated the need for human operators. By 1880, there was one telephone for every thousand residents of the United States.

Long-distance telephone calls

Long-distance telephone service could not develop until the technology improved to strengthen the telephone signal for traveling on telephone lines over long distances. In an effort to enter this market, the Western Union Company hired inventor Thomas Edison (1847–1931) to improve Bell's technology. Western Union, however, eventually sold its telephone technology to Bell Telephone. In 1885, Bell Telephone formed a subsidiary company for developing long-distance telephone service. It was called the American Telephone and Telegraph Company, or AT&T.

The first telephone lines used iron wires. Replacing them with copper wires allowed service to reach the distance from Boston, Massachusetts , to Chicago, Illinois . By 1900, Bell engineers had invented loading coils, which wrapped around the main conductor wires to improve signal strength. In 1906, scientist Lee de Forest (1873–1961) invented the audion tube. This device allowed the telephone signal to be strengthened, or amplified, at key points along the telephone lines. At the beginning of the twentieth century, there was one telephone for every one hundred people in the United States.

Breaking Up AT&T

In the early days of long-distance telephone service, AT&T refused to allow other telephone companies to have access to its network of telephone lines. Some companies began to build their own lines. This created a threat of competition. At the same time, there was political pressure for AT&T to grant access to its lines to prevent AT&T from having a monopoly on long-distance service.

AT&T soon learned that by leasing its lines to other companies, it could boost its profits while also discouraging the construction of competitive networks of lines. Leasing its lines to other companies eased the political pressure to break up AT&T. Over time, AT&T bought smaller companies that had trouble competing against AT&T and its superior financial resources. In this way AT&T dominated telephone service through most of the twentieth century.

In the 1970s, AT&T faced antitrust lawsuits from the federal government and a long-distance service competitor, MCI. By 1982, AT&T and the federal government reached an agreement to reorganize twenty-two of AT&T's regional telephone service companies into seven companies that became independent of AT&T. In exchange for getting rid of these companies, AT&T was allowed to remain in the businesses for long-distance service and telecommunications equipment, and to enter the business of manufacturing computer equipment.

In June 1914, AT&T finished a long-distance line between New York and San Francisco, California . The company tested the line that year and officially demonstrated it in January 1915 at the Panama-Pacific Exposition. In September 1915, Theodore N. Vail successfully tested a radio telephone communication from New York to San Francisco.

Just one month later the first transatlantic radio telephone communication was made between Arlington, Virginia , and Paris, France. Signal quality was poor, so another ten years passed before usable transatlantic telephone service occurred. The first transatlantic cable allowed electrical telephone service between American and Europe in 1956.

Telephone

views updated Jun 11 2018

Telephone




Although there are others who claim to have done so first, the telephone was invented in 1875 by a Scot, Alexander Graham Bell (1847–1922). His invention enabled people to talk to one another across vast distances. Within twenty years, telephones were widespread in the homes of the wealthy in the United States and in Europe. The laying of the first transatlantic telephone cable in 1956 began to create what is known as the "global village." In the twenty-first century, the principles of telephony invented by Bell are behind innovations such as fax machines and the Internet (see entry under 1990s—The Way We Lived in volume 5). Although telephone messages are now transmitted using satellites and digital signals, the telephone of the twenty-first century remains much as Bell anticipated.

Like many other things, the telephone was invented partly by accident. In the 1870s, the telegraph was the quickest way of sending messages over a long distance. But Bell hoped to speed up the system by making it possible to send more than one message at a time. He created a device that could convert sounds into electrical pulses and transmit them down a wire. From there, it was a short step to developing a machine that could carry the human voice. He was issued patent number 174465 on March 7, 1876. Soon after, he made the first telephone call, commanding his assistant Thomas Augustus Watson (1854–1934), who was in the next room: "Mr. Watson, come here! I want you!"

Bell's invention transformed the way people thought about distance, travel, and their communities. The telephone opened the way for long-distance gossip in a way that was impossible by telegraph, the older method of sending messages, yet in many ways the changes brought by the telephone were subtle and gradual. For a start, it did not change much in the way of the physical environment. The device itself was always quite small, stuck out of the way in hallways and booths. Where the telephone had its greatest impact was on the structure of society itself. As home telephones became more affordable in the 1920s and 1930s, people began using them as part of their social lives. For some commentators, this marked the beginning of a trend towards people becoming more private and self-centered. For others, however, the telephone simply freed people from having to travel to deliver simple messages. Either way, the telephone changed the way people lived their lives.

The telephone led to the growth of a whole range of services never before available. Police and firefighters could be called by the public from special telephone boxes on the street. (As more and more people acquired telephones, this practice was replaced beginning in the 1960s by the 911 system of alerting emergency services.) Telephone companies began to offer "wake-up" calls and messaging services. "Cold calling," whereby a salesperson uses the phone book to find new customers, became a useful but hated way to find new business. The arts and the media also felt the effect. The TV or radio phone-in became a cheap way for broadcasters to fill airtime. The plots of detective fiction (see entry under 1930s—Print Culture in volume 2) of the 1930s and 1940s often turn on a well-timed telephone call. Comedy routines from the early days of film include telephone jokes. Even in the twenty-first century, the telephone is a source of humor in shows from Frasier (see entry under 1990s—TV and Radio in volume 5) to The Simpsons (see entry under 1980s—TV and Radio in volume 5).

By the 1930s, most households in America at least had access to a telephone. People could be contacted more easily, and they in turn could make contact with the outside world. The trend continued throughout the twentieth century and into the twenty-first. By the 1980s, documents could be transmitted by fax while personal computers (see entry under 1970s—The Way We Lived in volume 4) "talked" to one another using modems that connected to telephone lines. Car telephones were available in the 1960s, but it was in the 1990s that hand-held mobile telephones became cheap enough for most people to own. They even became a fashion item. By the beginning of the twenty-first century, the video telephone had moved out of science fiction and into offices and some homes. Cellular phones (see entry under 1990s—The Way We Lived in volume 5), satellite (see entry under 1950s—The Way We Lived in volume 3) links, and the Internet meant that in 2002 there were few places on earth where one could not be reached by telephone.

Voicemail, answering machines, automated information services, and a host of other systems have made the telephone the most powerful communication tool of the early twenty-first century. But perhaps the best measure of the telephone's importance is that it is taken for granted. Telephones work behind the scenes so that in 2002, more than half of all telephone calls take place between machines, with no human intervention. In the twenty-first century, not having access to a telephone is a serious form of deprivation, and the multibillion-dollar telecommunications industry is fundamental to the world economy. Whether for medical emergencies, high-powered business deals, or ordering pizza (see entry under 1940s—Food and Drink in volume 3), the telephone remains an essential part of twenty-first century life.


—Chris Routledge


For More Information

Fischer, Claude S. America Calling: A Social History of the Telephone to 1940. Berkeley: University of California Press, 1992.

Gearhart, Sarah. The Telephone. New York: Atheneum Books for Young Readers, 1999.

Holland, Gini. Telephones. New York: Benchmark Books, 1996.

Oxlade, Chris. Telecommunications. Austin, TX: Raintree Steck-Vaughn, 1997.

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

Telephone

views updated May 23 2018

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 (18341874) 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 (18471922). In a quirk of fate, American inventor Elisha Gray (18351901) 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 ]