Telephone
Telephone, instrument that sends
and receives voice messages and data. Telephones convert speech and data to
electrical energy, which is sent great distances. Modern technology has made
the telephone much more portable, convenient, and versatile. Lightweight,
handheld cell phones make it possible to place and receive calls on-the-go in
many locations and at any time. Traditional telephones now link with radio,
Internet, and satellite services as part of global telecommunications.
Telephones play a vital
role in business and the economy, as well as in the personal and family lives
of individuals. Telephones also save lives and provide security by making it
possible to summon help quickly in an emergency (as in the 911 service in the
United States) and contact law enforcement or medical services. The telephone
has other uses that do not involve one person talking to another. Instead, an
automated menu can allow a caller to pay bills, obtain prerecorded information,
or retrieve messages from an answering machine. In 2004 there were 606 main
telephone lines per 1,000 people in the United States and 566 main telephone
lines per 1,000 people in Canada.
About half of the information
passing through telephone lines occurs entirely between special-purpose
telephones, such as computers with modems. A modem converts the digital bits of
a computer’s output to an audio tone, which is then converted to an electrical
signal and passed over telephone lines to be decoded by a modem attached to a
computer at the receiving end. Another special-purpose telephone is a facsimile
machine, or fax machine, which produces a duplicate of a document at a distant
point.
II
|
PARTS OF A TELEPHONE
|
A basic telephone set
contains a transmitter that transfers the caller’s voice; a receiver that
amplifies sound from an incoming call; a rotary or push-button dial; a ringer
or alerter; and a small assembly of electrical parts, called the antisidetone
network, that keeps the caller’s voice from sounding too loud through the
receiver. If it is a two-piece telephone set, the transmitter and receiver are
mounted in the handset, the ringer is typically in the base, and the dial may
be in either the base or handset. The handset cord connects the base to the
handset, and the line cord connects the telephone to the telephone line.
More sophisticated telephones
may vary from this pattern. A speakerphone has a microphone and speaker in the
base in addition to the transmitter and receiver in the handset. Speakerphones
allow callers’ hands to be free, and allow more than two people to listen and
speak during a call. In a cordless phone, the handset cord is replaced by a
radio link between the handset and base, but a line cord is still used. This
allows a caller to move about in a limited area while on the telephone. A
cellular phone has extremely miniaturized components that make it possible to
combine the base and handset into one handheld unit. No line or handset cords
are needed with a cellular phone. A cellular phone permits more mobility than a
cordless phone.
A
|
Transmitter
|
There are two common kinds
of telephone transmitters: the carbon transmitter and the electret transmitter.
The carbon transmitter is constructed by placing carbon granules between metal
plates called electrodes. One of the metal plates is a thin diaphragm that
takes variations in pressure caused by sound waves and transmits these
variations to the carbon granules. The electrodes conduct electricity that
flows through the carbon. Variations in pressure caused by sound waves hitting
the diaphragm cause the electrical resistance of the carbon to vary—when the
grains are squeezed together, they conduct electricity more easily; and when
they are far apart, they conduct electricity less efficiently. The resultant
current varies with the sound-wave pressure applied to the transmitter.
The electret transmitter is
composed of a thin disk of metal-coated plastic and a thicker, hollow metal
disk. In the handset, the plastic disk is held slightly above most of the metal
disk. The plastic disk is electrically charged, and an electric field is
created in the space where the disks do not touch. Sound waves from the
caller’s voice cause the plastic disk to vibrate, which changes the distance
between the disks, and so changes the intensity of the electric field between
them. The variations in the electric field are translated into variations of
electric current, which travels across telephone lines. An amplifier using
transistors is needed with an electret transmitter to obtain sufficiently
strong variations of electric current.
B
|
Receiver
|
The receiver of a telephone
set is made from a flat ring of magnetic material with a short cuff of the same
material attached to the ring’s outer rim. Underneath the magnetic ring and
inside the magnetic cuff is a coil of wire through which electric current,
representing the sounds from the distant telephone, flows. A thin diaphragm of
magnetic material is suspended from the inside edges of the magnetic ring so it
is positioned between the magnet and the coil. The magnetic field created by
the magnet changes with the current in the coil and makes the diaphragm
vibrate. The vibrating diaphragm creates sound waves that replicate the sounds
that were transformed into electricity by the other person’s transmitter.
C
|
Alerter
|
The alerter in a telephone
is usually called the ringer, because for most of the telephone’s history, a
bell was used to indicate a call. The alerter responds only to a special
frequency of electricity that is sent by the exchange in response to the
request for that telephone number. Creating an electronic replacement for the
bell that can provide a pleasing yet attention-getting sound at a reasonable
cost was a surprisingly difficult task. For many people, the sound of a bell is
still preferable to the sound of an electronic alerter. However, since a
mechanical bell requires a certain amount of space in the telephone to be
effective, smaller telephones mandate the use of electronic alerters.
D
|
Dial
|
The telephone dial has
undergone major changes in its history. Two forms of dialing still exist within
the telephone system: dial pulse from a rotary dial, and multifrequency tone,
which is commonly called by its original trade name of Touch-Tone, from a
push-button dial.
In a rotary dial, the
numerals one to nine, followed by zero, are placed in a circle behind round holes
in a movable plate. The user places a finger in the hole corresponding to the
desired digit and rotates the movable plate clockwise until the user’s finger
hits the finger stop; then the user removes the finger. A spring mechanism
causes the plate to return to its starting position, and, while the plate is
turning, the mechanism opens an electrical switch the number of times equal to
the dial digit. Zero receives ten switch openings since it is the last digit on
the dial. The result is a number of 'dial pulses' in the electrical current
flowing between the telephone set and the exchange. Equipment at the exchange
counts these pulses to determine the number being called.
The rotary dial has been
used since the 1920s. But mechanical dials are expensive to repair and the
rotary-dialing process itself is slow, especially if a long string of digits is
dialed. The development of inexpensive and reliable amplification provided by
the introduction of the transistor in the 1960s made practical the design of a
dialing system based on the transmission of relatively low power tones instead
of the higher-power dial pulses.
Today most telephones have push
buttons instead of a rotary dial. Touch-Tone is an optional service, and
telephone companies still maintain the ability to receive pulse dialing.
Push-button telephones usually have a switch on the base that the customer can
set to determine whether the telephone will send pulses or tones.
E
|
Business Telephones
|
A large business will
usually have its own switching machine called a Private Branch Exchange (PBX),
with hundreds or possibly thousands of lines, all of which can be reached by
dialing one number. The extension telephones connected to the large business’s
PBX are often identical to the simple single-line instruments used in
residences. The telephones used by small businesses, which do not have their
own PBX, must incorporate the capability of accessing several telephone lines
and are called multiline sets. The small-business environment usually requires
the capability of transferring calls from one set to another as well as
intercom calls, which allow one employee to call another without using an
outside telephone line.
F
|
Cellular Telephones
|
Cellular Radio Telephone
Students use a cellular radio telephone,
also known as a cell phone. As cell phones have grown in popularity, they have
also decreased in size.
A cellular telephone is
designed to give the user maximum freedom of movement while using a telephone.
A cellular telephone uses radio signals to communicate between the set and an
antenna. The served area is divided into cells something like a honeycomb, and
an antenna is placed within each cell and connected by telephone lines to one
exchange devoted to cellular-telephone calls. This exchange connects cellular
telephones to one another or transfers the call to a regular exchange if the
call is between a cellular telephone and a noncellular telephone. The special
cellular exchange, through computer control, selects the antenna closest to the
telephone when service is requested. As the telephone roams, the exchange
automatically determines when to change the serving cell based on the power of
the radio signal received simultaneously at adjacent sites. This change occurs
without interrupting conversation. Practical power considerations limit the
distance between the telephone and the nearest cellular antenna, and since
cellular phones use radio signals, it is very easy for unauthorized people to
access communications carried out over cellular phones. Currently, digital
cellular phones are gaining in popularity because the radio signals are harder
to intercept and decode.
III
|
MAKING A TELEPHONE CALL
|
A telephone call starts
when the caller lifts a handset off the base. This closes an electrical switch
that initiates the flow of a steady electric current over the line between the
user’s location and the exchange. The exchange detects the current and returns
a dial tone, a precise combination of two notes that lets a caller know the
line is ready.
Once the dial tone is
heard, the caller uses a rotary or push-button dial mounted either on the
handset or base to enter a sequence of digits, the telephone number of the
called party. The switching equipment in the exchange removes the dial tone
from the line after the first digit is received and, after receiving the last
digit, determines whether the called party is in the same exchange or a
different exchange. If the called party is in the same exchange, bursts of
ringing current are applied to the called party’s line. Each telephone contains
a ringer that responds to a specific electric frequency. When the called party
answers the telephone by picking up the handset, steady current starts to flow
in the called party’s line and is detected by the exchange. The exchange then
stops applying ringing and sets up a connection between the caller and the
called party.
If the called party is
in a different exchange from the caller, the caller’s exchange sets up a
connection over the telephone network to the called party’s exchange. The
called exchange then handles the process of ringing, detecting an answer, and notifying
the calling exchange and billing machinery when the call is completed (in
telephone terminology, a call is completed when the called party answers, not
when the conversation is over).
When the conversation is over,
one or both parties hang up by replacing their handset on the base, stopping
the flow of current. The exchange then initiates the process of taking down the
connection, including notifying billing equipment of the duration of the call
if appropriate. Billing equipment may or may not be involved because calls
within the local calling area, which includes several nearby exchanges, may be
either flat rate or message rate. In flat-rate service, the subscriber is
allowed an unlimited number of calls for a fixed fee each month. For message-rate
subscribers, each call involves a charge that depends on the distance between
the calling and called parties and the duration of the call. A long-distance
call is a call out of the local calling area and is always billed as a
message-rate call.
A
|
Switching
|
Telephone switching equipment
interprets the number dialed and then completes a path through the network to
the called subscriber. For long-distance calls with complicated paths through
the network, several levels of switching equipment may be needed. The automatic
exchange to which the subscriber’s telephone is connected is the lowest level
of switching equipment and is called by various names, including local
exchange, local office, central-office switch, or, simply, switch. Higher
levels of switching equipment include tandem and toll switches, and are not
needed when both caller and called subscribers are within the same local
exchange.
Before automatic exchanges were
invented, all calls were placed through manual exchanges in which a small light
on a switchboard alerted an operator that a subscriber wanted service. The
operator inserted an insulated electrical cable into a jack corresponding to
the subscriber requesting service. This allowed the operator and the subscriber
to converse. The caller told the operator the called party’s name, and the
operator used another cord adjacent to the first to plug into the called
party’s jack and then operated a key (another type of electrical switch) that
connected ringing current to the called party’s telephone. The operator
listened for the called party to answer, and then disconnected to ensure the
privacy of the call.
Today there are no telephones
served by manual exchanges in the United States. All telephone subscribers are
served by automatic exchanges, which perform the functions of the human
operator. The number being dialed is stored and then passed to the exchange’s
central computer, which in turn operates the switch to complete the call or
routes it to a higher-level switch for further processing.
Today’s automatic exchanges use
a pair of computers, one running the program that provides service, and the
second monitoring the operation of the first, ready to take over in a few
seconds in the event of an equipment failure.
Early telephone exchanges, a
grouping of 10,000 individual subscriber numbers, were originally given names
corresponding to their town or location within a city, such as Murray Hill or
Market. When the dialing area grew to cover more than one exchange, there was a
need for the dial to transmit letters as well as numbers. This problem was
solved by equating three letters to each digit on the dial except for the one
and the zero. Each number from two to nine represented three letters, so there
was room for only 24 letters. Q and Z were left off the dial
because these letters rarely appear in place-names. In dialing, the first two
letters of each exchange name were used ahead of the rest of the subscriber’s
number, and all exchange names were standardized as two letters and a digit. Eventually
the place-names were replaced with their equivalent digits, giving us our
current U.S. and Canadian seven- or ten-digit telephone numbers. In other parts
of the world, a number may consist of more or less than seven digits.
The greatly expanded information-processing
capability of modern computers permits Direct Distance Dialing, with which a
subscriber can automatically place a call to a distant city without needing the
services of a human operator to determine the appropriate routing path through
the network. Computers in the switching machines used for long-distance calls
store the routing information in their electronic memory. A toll-switching
machine may store several different possible routes for a call. As telephone
traffic becomes heavier during the day, some routes may become unavailable. The
toll switch will then select a less direct alternate route to permit the
completion of the call.
B
|
Transmission
|
Fiber-Optic Strands
A strand of fiber-optic cable reflects
the light that passes through it back into the fiber, so light cannot escape
the strand. Fiber-optic cables carry more information, suffer less
interference, and require fewer signal repeaters over long distances than
wires.
Calling from New York City
to Hong Kong involves using a path that transmits electrical energy halfway
around the world. During the conversation, it is the task of the transmission
system to deliver that energy so that the speech or data is transmitted clearly
and free from noise. Since the telephone in New York City does not know whether
it is connected to a telephone next door or to one in Hong Kong, the amount of
energy put on the line is not different in either case. However, it requires
much more energy to converse with Hong Kong than with next door because energy
is lost in the transmission. The transmission path must provide amplification
of the signal as well as transport.
Analog transmission, in which
speech or data is converted directly into a varying electrical current, is
suitable for local calls. But once the call involves any significant distance,
the necessary amplification of the analog signal can add so much noise that the
received signal becomes unintelligible. For long-distance calls, the signal is
digitized, or converted to a series of pulses that encodes the information.
When an analog electrical
signal is digitized, samples of the signal’s strength are taken at regular
intervals, usually about 8,000 samples per second. Each sample is converted
into a binary form, a number made up of a series of 1s and 0s. This number is
easily and swiftly passed through the switching system. Digital transmission
systems are much less subject to interfering noise than are analog systems. The
digitized signal can then be passed through a digital-to-analog converter (DAC)
at a point close to the receiving party, and converted to a form that the ear
cannot distinguish from the original signal.
There are several ways a
digital or analog signal may be transmitted, including coaxial and fiber-optic
cables and microwave and longwave radio signals sent along the ground or
bounced off satellites in orbit around the earth. A coaxial wire, like the wire
between a videocassette recorder, or VCR (see Video Recording), and a
television set, is an efficient transmission system. A coaxial wire has a
conducting tube surrounding another conductor. A coaxial cable contains several
coaxial wires in a common outer covering. The important benefit of a coaxial
cable over a cable composed of simple wires is that the coaxial cable is more
efficient at carrying very high frequency currents. This is important because
in providing transmission over long distances, many telephone conversations are
combined using frequency-modulation (FM) techniques similar to the combining of
many channels in the television system. The combined signal containing hundreds
of individual telephone conversations is sent over one pair of wires in a
coaxial cable, so the signal has to be very clear.
Coaxial cable is expensive
to install and maintain, especially when it is lying on the ocean floor. Two
methods exist for controlling this expense. The first consists of increasing
the capacity of the cable and so spreading the expense over more users. The
installation of the first transatlantic submarine coaxial telephone cable in
1956 provided only about 30 channels, but the number of submarine cable
channels across the ocean has grown to thousands with the addition of only a
few more cables because of the greatly expanded capacity of each new coaxial
cable.
Another telephone-transmission method
uses fiber-optic cable, which is made of bundles of optical fibers (see Fiber
Optics), long strands of specially made glass encased in a protective coating.
Optical fibers transmit energy in the form of light pulses. The technology is
similar to that of the coaxial cable, except that the optical fibers can handle
tens of thousands of conversations simultaneously.
Another approach to long-distance
transmission is the use of radio. Before coaxial cables were invented, very
powerful longwave (low frequency) radio stations were used for intercontinental
calls. Only a few calls could be in progress at one time, however, and such
calls were very expensive. Microwave radio uses very high frequency radio waves
and has the ability to handle a large number of simultaneous conversations over
the same microwave link. Because cable does not have to be installed between
microwave towers, this system is usually cheaper than coaxial cable. On land,
the coaxial-cable systems are often supplemented with microwave-radio systems.
The technology of microwave
radio is carried one step further by the use of communications satellites. Most
communications satellites are in geosynchronous orbit—that is, they orbit the
earth once a day over the equator, so the satellite is always above the same
place on the earth’s surface. That way, only a single satellite is needed for
continuous service between two points on the surface, provided both points can
be seen from the satellite. Even considering the expense of a satellite, this
method is cheaper to install and maintain per channel than using coaxial cables
on the ocean floor. Consequently, satellite links are used regularly in long-distance
calling. Since radio waves, while very fast, take time to travel from one point
to another, satellite communication does have one serious shortcoming: Because
of the satellite’s distance from the earth, there is a noticeable lag in
conversational responses. As a result, many calls use a satellite for only one
direction of transmission, such as from the caller to the receiver, and use a
ground microwave or coaxial link for receiver-to-caller transmission.
A combination of microwave,
coaxial-cable, optical-fiber, and satellite paths now link the major cities of
the world. The capacity of each type of system depends on its age and the
territory covered, but capacities generally fall into the following ranges:
Frequency modulation over a simple pair of wires like the earliest telephone
lines yields tens of circuits (a circuit can transmit one telephone
conversation) per pair; coaxial cable yields hundreds of circuits per pair of
conductors, and thousands per cable; microwave and satellite transmissions yield
thousands of circuits per link; and optical fiber has the potential for tens of
thousands of circuits per fiber.
IV
|
TELEPHONE SERVICES
|
In the United States and
Canada, universal service was a stated goal of the telephone industry during
the first half of the 20th century—every household was to have its own
telephone. This goal has now been essentially reached, but before it became a
reality, the only access many people had to the telephone was through pay (or
public) telephones, usually placed in a neighborhood store. A pay telephone is
a telephone that may have special hardware to count and safeguard coins or,
more recently, to read the information off credit cards or calling cards.
Additional equipment at the exchange responds to signals from the pay phone to
indicate to the operator or automatic exchange how much money has been
deposited or to which account the call will be charged. Today the pay phone
still exists, but it usually serves as a convenience rather than as primary
access to the telephone network. The explosive growth of cell phones has
greatly reduced the use of pay phones. The FCC estimates that more than 1
million pay phones have been removed from service since the mid-1990s.
Computer-controlled exchange switches
make it possible to offer a variety of extra services to both the residential
and the business customer. Some services to which users may subscribe at extra
cost are call waiting, in which a second incoming call, instead of receiving a
busy signal, hears normal ringing while the subscriber hears a beep
superimposed on the conversation in progress; and three-way calling, in which a
second outgoing call may be placed while one is already in progress so that three
subscribers can then talk to each other. Some services available to users
within exchanges with the most-modern transmission systems are: caller ID, in
which the calling party’s number is displayed to the receiver (with the calling
party’s permission—subscribers can elect to make their telephone number hidden
from caller-ID services) on special equipment before the call is answered; and
repeat dialing, in which a called number, if busy, will be automatically
redialed for a certain amount of time.
For residential service, voice
mail can either be purchased from the telephone company or can be obtained by
purchasing an answering machine. An answering machine usually contains a
regular telephone set along with the ability to detect incoming calls and to
record and play back messages, with either an audiotape or a digital system.
After a preset number of rings, the answering machine plays a prerecorded
message inviting the caller to leave a message to be recorded.
Toll-free 800 numbers are a very
popular service. Calls made to a telephone number that has an 800 area code are
billed to the called party rather than to the caller. This is very useful to
any business that uses mail-order sales, because it encourages potential
customers to call to place orders. A less expensive form of 800-number service
is now available for residential subscribers.
In calling telephone numbers
with area codes of 900, the caller is billed an extra charge, often on a
per-minute basis. The use of these numbers has ranged from collecting
contributions for charitable organizations, to businesses that provide
information for which the caller must pay.
While the United States and
Canada are the most advanced countries in the world in telephone-service
technologies, most other industrialized nations are not far behind. An
organization based in Geneva, Switzerland, called the International
Telecommunication Union (ITU), works to standardize telephone service
throughout the world. Without its coordinating activities, International Direct
Distance Dialing (a service that provides the ability to place international
calls without the assistance of an operator) would have been extremely
difficult to implement. Among its other services, the ITU creates an
environment in which a special service introduced in one country can be quickly
duplicated elsewhere.
V
|
THE HISTORY OF THE TELEPHONE
|
Alexander Graham Bell
Alexander Graham Bell’s attempts to
electrically transmit speech resulted in a patent for the telephone in 1876.
Bell founded the Bell Telephone Company to manufacture telephones and operate
the telephone network. Bell’s company, later known as AT&T Corp., grew to
dominate the telecommunications industry until a 1984 antitrust suit divested
the company of its local telephone networks.
The history of the invention
of the telephone is a stormy one. A number of inventors contributed to carrying
a voice signal over wires. In 1854 the French inventor Charles Bourseul
suggested that vibrations caused by speaking into a flexible disc or diaphragm
might be used to connect and disconnect an electric circuit, thereby producing
similar vibrations in a diaphragm at another location, where the original sound
would be reproduced. A few years later, the German physicist Johann Philip Reis
invented an instrument that transmitted musical tones, but it could not
reproduce speech. An acoustic communication device that could transmit speech
was developed around 1860 by an Italian American inventor, Antonio Meucci. The
first to achieve commercial success and inaugurate widespread use of the
telephone, however, was a Scottish-born American inventor, Alexander Graham
Bell, a speech teacher in Boston, Massachusetts.
Bell had built an experimental
telegraph, which began to function strangely one day because a part had come
loose. The accident gave Bell insight into how voices could be reproduced at a
distance, and he constructed a transmitter and a receiver, for which he
received a patent on March 7, 1876. On March 10, 1876, as he and his assistant,
Thomas A. Watson, were preparing to test the mechanism, Bell spilled some acid
on himself. In another room, Watson, next to the receiver, heard clearly the
first telephone message: “Mr. Watson, come here; I want you.”
Early Telephones
While working on sound transmission for
the deaf, Alexander Graham Bell discovered that steady electric current can be
altered to resemble the vibrations made by the human voice. In 1876 he patented
a device that sent speech along wires and called it the telephone. Early models
of the telephone include Edison’s 1879 wall-mounted phone (left), the
candlestick design common in the 1920s and 1930s (bottom), and a 1937 “cradle”
telephone, a style popular since 1890 (shown right).
A few hours after Bell
had patented his invention, another American inventor, Elisha Gray, filed a
document called a caveat with the U.S. Patent Office, announcing that he was
well on his way to inventing a telephone. Other inventors, including Meucci and
Amos E. Dolbear, also made claim to having invented the telephone. Lawsuits
were filed by various individuals, and Bell’s claim to being the inventor of
the first telephone had to be defended in court some 600 times. Gray’s case was
decided in Bell’s favor. Meucci’s case was never resolved because Meucci died
before it reached the Supreme Court of the United States.
A
|
Advances in Technology
|
Satellite Telephone
A telephone company employee displays a
handset used in the firm's satellite telephone system. Satellite telephones
enable direct communications to telephone networks from anywhere on the globe.
Users can also communicate even if no wired or cellular telephone network
exists.
After the invention of the
telephone instrument itself, the second greatest technological advance in the
industry may have been the invention of automatic switching. The first
automatic exchanges were called Strowger switches, after Almon Brown Strowger,
an undertaker in Kansas City, Missouri, who invented the system because he
thought his town’s human operators were steering prospective business to his
competitors. Strowger received a patent for the switches in 1891.
Long-distance telephony was
established in small steps. The first step was the introduction of the
long-distance telephone, originally a special highly efficient instrument
permanently installed in a telephone company building and used for calling
between cities. The invention at the end of the 19th century of the loading
coil (a coil of copper wire wound on an iron core and connected to the cable
every mile or so) increased the speaking range to approximately 1,000 miles.
Until the 1910s the long-distance service used repeaters, electromechanical
devices spaced along the route of the call that amplified and repeated
conversations into another long-distance instrument. The obvious shortcomings
of this arrangement were overcome with the invention of the triode vacuum tube,
which amplified electrical signals. In 1915 vacuum-tube repeaters were used to
initiate service from New York City to San Francisco, California.
The vacuum tube also made
possible the development of longwave radio circuits that could span oceans.
Sound quality on early radio circuits was poor, and transmission subject to
unpredictable interruption. In the 1950s the technology of the coaxial-cable
system was combined with high-reliability vacuum-tube circuits in an undersea
cable linking North America and Europe, greatly improving transmission quality.
Unlike the first transatlantic telegraph cable placed in service in 1857, which
failed after two months, the first telephone cable (laid in 1956) served many
years before becoming obsolete. The application of digital techniques to transmission,
along with undersea cable and satellites, finally made it possible to link
points halfway around the earth with a circuit that had speech quality almost
as good as that between next-door neighbors.
Improved automatic-switching systems
followed the gradual improvement in transmission technology. Until Direct
Distance Dialing became available, all long-distance calls still required the
assistance of an operator to complete. By adding a three-digit area code in
front of the subscriber’s old number and developing more sophisticated
common-control-switching machines, it became possible for subscribers to
complete their own long-distance calls. Today customer-controlled international
dialing is available between many countries.
B
|
Evolution of the Telephone Industry
|
In the late 1800s, the
Bell Telephone Company (established in 1877 by Alexander Graham Bell and
financial backers Gardiner Greene Hubbard, a lawyer, and Thomas Sanders, a
leather merchant) strongly defended its patents in order to exclude others from
the telephone business. After these patents expired in 1893 and 1894,
independent telephone companies were started in many cities and most small
towns. A period of consolidation followed in the early 1900s, and eventually
about 80 percent of the customers in the United States and many of those in
Canada were served by the American Telephone and Telegraph Company (AT&T),
which had bought the Bell Telephone Company in 1900. AT&T sold off its
Canadian interests in 1908.
From 1885 to 1887 and
from 1907 to 1919 AT&T was headed by Theodore Vail, whose vision shaped the
industry for most of the 20th century. At that time, AT&T included 22
regional operating companies, each providing telephone service to an area
comprising a large city, state, or group of states. In addition to owning
virtually all of the long-distance circuits in use in the United States,
AT&T owned the Western Electric Company, which manufactured most of the
equipment. Such a corporate combination is called a vertically integrated
monopoly because it dominates all facets of a business.
Both the long-distance part of
AT&T and the operating companies were considered to be “natural
monopolies,” and by law were decreed to be the sole provider of telephone
service within a designated area. More than 5,000 independent companies
remained, but each independent was also a monopoly with an exclusive service
region. This arrangement reduced the costs associated with more than one
company stringing wires in an area, and eliminated the early problems that had
arisen when customers of one company serving a region wished to call customers
of another company serving the same area. In exchange for the absence of
competition, the companies were regulated by various levels of government,
which told them what services they must provide and what prices they could
charge.
During this time, telephone
sets were never sold to the customer—they were leased as part of an overall
service package that included the telephone, the connecting lines to the
exchange, and the capability of calling other customers. In this way, the
telephone company was responsible for any problems, whether they arose from
equipment failures, damage to exposed wires, or even the conduct of operators
on their job. If a telephone set broke, it was fixed or replaced at no charge.
Since stringing wires between
exchanges and users was a major part of the cost of providing telephone
service, especially in rural environments, early residential subscribers often
shared the same line. These were called party lines—as opposed to private, or
single-party, lines. When one subscriber on a party line was making a telephone
call, the other parties on the line could not use the line. Unfortunately, they
could listen to the conversation, thereby compromising its privacy. Such
arrangements also meant that, unless special equipment was used, all the
telephones on the line would ring whenever there was a call for any of the
parties. Each party had a distinct combination of short and long rings to
indicate whether the call was for that house or another party.
Business telephones were usually
private lines. A business could not afford to have its service blocked by
another user. This meant that business service was more expensive than
residential service. Businesses continued to be charged more for their private
lines than were subscribers with private lines in homes. This subsidization of
telephones in homes permeated the government-regulated rate structure of the
telephone industry until about 1980. Long-distance service was priced
artificially high, and the consequent extra revenues to the telephone company
were used to keep the price of residential service artificially low.
While most consumers were
happy with the control of all equipment by the telephone companies, some were
not. Also, because of strong vertical integration within AT&T, the purchase
of equipment from independent manufacturers was tightly controlled. AT&T
initially refused to allow the independently manufactured Carterphone, a device
that linked two-way-radio equipment to a telephone, to be connected to its
network. After protracted lawsuits, AT&T agreed in 1968 to allow the
connection of independently manufactured telephones to its network, provided they
met legal standards set by the Federal Communications Commission (FCC). While
the AT&T agreement did not directly involve the other telephone companies
in the country, over time the entire industry followed AT&T’s lead.
In 1974 MCI Communications
Corporation challenged AT&T about its right to maintain a monopoly over
long-distance service. Antitrust proceedings were brought, and eventually
settled in 1982 in a consent decree that brought about the breakup of AT&T.
In a consent decree, the federal government agrees to stop proceedings against
a company in return for restrictions on or changes in the company.
The antitrust proceedings were
dropped when AT&T agreed to sell off its local operating companies,
retaining the long-distance network and manufacturing companies. The former
AT&T operating companies were regrouped into seven Regional Holding
Companies (RHCs), which were initially restricted from engaging in any business
other than telephone service within their assigned service area. The RHCs promptly
began sidestepping these restrictions by setting up subsidiaries to operate in
the unregulated environment and seeking legislation to further remove
restrictions. At the same time, alternate long-distance carriers, such as MCI
and Sprint, sought legislation to keep AT&T under as much regulation as
possible while freeing themselves from any regulation.
C
|
The Telephone Industry Today
|
In 1996 the U.S. government
enacted the Telecommunications Reform Act, which removed government rules
preventing local and long-distance phone companies, cable television operators,
broadcasters, and wireless services from directly competing with one another.
The act spurred consolidation in the industry, as regional companies joined
forces to create telecommunications giants that provided telephone, wireless,
cable, and Internet services.
In other countries, until
the 1990s, most of the telephone companies were owned by each nation’s central
government and operated as part of the post office, an arrangement that
inevitably led to tight control. Many countries are now privatizing telephone
service. In order to escape government regulation at home, U.S. companies are
investing heavily in the phone systems of other countries. For example, in 1995
AT&T announced it would attempt to gain a share of the market for telephone
services in India. In a reverse trend, European companies are investing in U.S.
long-distance carriers.
Other major markets for
telephone companies are opening up around the globe as the developing world
becomes more technologically advanced. Nonindustrial countries are now trying
to leapfrog their development by encouraging private companies to install only
the latest technology. In remote places in India and Africa, the use of solar
cells is now making it possible to introduce telephones in areas still without
electricity.
VI
|
RECENT DEVELOPMENTS
|
The introduction of radio
into the telephone set has been the most important recent development in
telephone technology, permitting first the cordless phone and now the cellular
phone. In addition to regular telephone service, modern cellular phones also
provide wireless Internet connections, enabling users to send and receive
electronic mail and search the World Wide Web. Cell phones have taken on major
importance in some developing countries where landlines for telephones often do
not exist outside of large cities. In remote rural areas an individual who owns
a cell phone may charge a small fee to let others use the phone service. Cell
phone service can have major economic impacts in impoverished regions, allowing
access to banking, providing information on prices of crops, and establishing
small-business contacts.
Answering machines and phones
with dials that remember several stored numbers (repertory dials) have been
available for decades, but because of their expense and unreliability were
never as popular as they are today. Multifunctional telephones that use
microprocessors and integrated circuits have overcome both these barriers to
make repertory dials a standard feature in most phones sold today. Many
multifunctional telephones also include automatic answering and
message-recording capability.
Videophones are devices that use
a miniature video camera to send images as well as voice communication.
Videophones can be connected to regular telephone lines or their messages can
be sent via wireless technology. Since the transmission of a picture requires
much more bandwidth (a measure of the amount of data a system can transmit per
period of time) than the transmission of voice, the high cost of transmission
facilities has limited the use of videophone service. This problem is being
overcome by technologies that compress the video information, and by the
steadily declining cost of transmission and video-terminal equipment. Video
service is now used to hold business “teleconferences” between groups in
distant cities using high-capacity transmission paths with wide bandwidth.
Videophones suitable for conversations between individuals over the normal
network are commercially available, but because they provide a picture inferior
to that of a television set, have not proven very popular. Television news
organizations adopted the use of videophones to cover breaking news stories in
remote areas. Their use escalated in 2001 during the U.S. war against
terrorists and the Taliban regime in Afghanistan.
Telecommunications companies are
rapidly expanding their use of digital technology, such as Digital Subscriber
Line (DSL) or Integrated Services Digital Network (ISDN), to allow users to get
more information faster over the telephone. Telecommunications companies are
also investing heavily in fiber optic cable to meet the ever-increasing demand
for increased bandwidth.
Telephone service over the
Internet using a computer or special equipment has grown in popularity. Called
Voice over Internet Protocol (VoIP), the technology requires a broadband
Internet connection but can send calls that are received by someone using an analog
phone line. Special adapter boxes also allow calls over the Internet from a
regular analog telephone. Long distance and international calls can be
transmitted at much lower cost depending on the service.
As bandwidth continues to
improve, an instrument that functions as a telephone, computer, and television
becomes more commercially viable. Such a device is now available, but its cost
will likely limit its widespread use in the early part of the 21st century.
As portable devices with
computer components and expanded memory capacity become more versatile, phone
service can be combined with wireless access to the Internet and media player
features. The introduction of the Apple iPhone in 2007 marked a trend toward
lightweight, handheld multipurpose devices. The iPhone can function as a mobile
phone, a camera, a media player, and a voicemail, e-mail, and text messaging
device, as well as a computer with Wi-Fi access to the World Wide Web.
No comments:
Post a Comment