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106-448: The group published its specifications as X/Open Portability Guide , starting with Issue 1 in 1985, and later as X/Open CAE Specification . In 1987, X/Open was incorporated as X/Open Company, Ltd. By March 1988, X/Open grew to 13 members: AT&T , Digital , Hewlett-Packard , Sun Microsystems , Unisys , NCR , Olivetti, Bull, Ericsson, Nixdorf, Philips, ICL, and Siemens. By 1990 the group had expanded to 21 members: in addition to

212-412: A thermionic tube or thermionic valve uses thermionic emission of electrons from a heated cathode for a number of fundamental electronic functions such as signal amplification and current rectification . The simplest vacuum tube, the diode invented in 1904 by John Ambrose Fleming , contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through

318-513: A limited liability company . In a filing with the South Dakota Secretary of State dated January 30, 2024, the reason given for the merger is that New York state law does not allow AT&T Corp. to be directly converted into an LLC. Although acquired by SBC in 2005, AT&T Corp. has remained a separate entity within the corporate structure of AT&T Inc. The merger, said to create “greater operational efficiencies”, will end

424-411: A radio broadcasting station , the station's large power amplifier is the transmitter and the broadcasting antenna is the interface between the power amplifier and the free space channel. The free space channel is the transmission medium and the receiver's antenna is the interface between the free space channel and the receiver. Next, the radio receiver is the destination of the radio signal, where it

530-527: A 171 conference room inn. The AT&T Learning Center won the commercial property known as Somerset County's Land Development Award that year. In 1992, Basking Ridge location would become a corporate headquarters just before AT&T leased the New York City, 550 Madison Avenue building to Sony in 1993. The corporate statue, known as " Golden Boy " was moved in 1992, from the former New York City headquarters to this current New Jersey headquarters. In 1992,

636-407: A Class 1 licensed private helipad , a two-story cafeteria, a wood-burning fireplace, an indoor waterfall at the entrance lobby, and a seven-acre created lake for flood control. The entire property was 130 acre and cost $ 219 million to construct. Later, across the street from the complex, AT&T purchased additional land and established its Learning Center in 1985, at 300 North Maple Avenue, to become

742-411: A better price for their goods. In Côte d'Ivoire , coffee growers share mobile phones to follow hourly variations in coffee prices and sell at the best price. On the macroeconomic scale, Lars-Hendrik Röller and Leonard Waverman suggested a causal link between good telecommunication infrastructure and economic growth. Few dispute the existence of a correlation although some argue it is wrong to view

848-438: A caveat for it in 1876. Gray abandoned his caveat and because he did not contest Bell's priority, the examiner approved Bell's patent on March 3, 1876. Gray had filed his caveat for the variable resistance telephone, but Bell was the first to document the idea and test it in a telephone.[88] Antonio Meucci invented a device that allowed the electrical transmission of voice over a line nearly 30 years before in 1849, but his device

954-441: A connection between two or more users. For both types of networks, repeaters may be necessary to amplify or recreate the signal when it is being transmitted over long distances. This is to combat attenuation that can render the signal indistinguishable from the noise. Another advantage of digital systems over analogue is that their output is easier to store in memory, i.e., two voltage states (high and low) are easier to store than

1060-495: A continuous range of states. Telecommunication has a significant social, cultural and economic impact on modern society. In 2008, estimates placed the telecommunication industry 's revenue at US$ 4.7 trillion or just under three per cent of the gross world product (official exchange rate). Several following sections discuss the impact of telecommunication on society. On the microeconomic scale, companies have used telecommunications to help build global business empires. This

1166-411: A corporate art consultant approached, artist sculptor, Elyn Zimmerman , to commission a 30-foot diameter project with fountain and seating area for the conference center courtyard gardens. In 1994, the project was completed and had one 34 ton granite boulder centered on top of the other boulders, which flowed water from the fountain designed by fountain engineer, Dr. Gerald Palevsky. AT&T occupancy at

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1272-555: A headquarters on 195 Broadway (close to what is now the World Trade Center site ). The property originally belonged to Western Union , of which AT&T held a controlling interest until 1913 when AT&T divested its interest as part of the Kingsbury Commitment . Construction of the current building began in 1912. Designed by William Welles Bosworth , who played a significant role in designing Kykuit ,

1378-406: A higher-frequency signal (known as the " carrier wave ") before transmission. There are several different modulation schemes available to achieve this [two of the most basic being amplitude modulation (AM) and frequency modulation (FM)]. An example of this process is a disc jockey's voice being impressed into a 96 MHz carrier wave using frequency modulation (the voice would then be received on

1484-450: A key advantage of digital signals over analogue signals. However, digital systems fail catastrophically when noise exceeds the system's ability to autocorrect. On the other hand, analogue systems fail gracefully: as noise increases, the signal becomes progressively more degraded but still usable. Also, digital transmission of continuous data unavoidably adds quantization noise to the output. This can be reduced, but not eliminated, only at

1590-433: A network of undersea surveillance cables for foreign submarine detection. AT&T was probably, according to internal employees, involved in this Sound Surveillance System ( SOSUS ). After completion, AT&T began commercial operations in cable laying for communications in 1955. The implementation of cables assured local and long-distance telephone or data services would provide revenue for the company. AT&T Long Lines

1696-474: A new building at 550 Madison Avenue . This new AT&T Building was designed by Philip Johnson and quickly became an icon of the new Postmodern architectural style. The building was completed in 1984, the very year of the divestiture of the Bell System. The building proved to be too large for the post-divestiture corporation and in 1993, AT&T leased the building to Sony , who then subsequently owned

1802-838: A new international frequency list and used in conformity with the Radio Regulation". According to the ITU's Radio Regulations adopted in Atlantic City, all frequencies referenced in the International Frequency Registration Board , examined by the board and registered on the International Frequency List "shall have the right to international protection from harmful interference". From a global perspective, there have been political debates and legislation regarding

1908-437: A person's age, interests, sexual preference and relationship status. In this way, these sites can play important role in everything from organising social engagements to courtship . Prior to social networking sites, technologies like short message service (SMS) and the telephone also had a significant impact on social interactions. In 2000, market research group Ipsos MORI reported that 81% of 15- to 24-year-old SMS users in

2014-491: A radio as the channel "96 FM"). In addition, modulation has the advantage that it may use frequency division multiplexing (FDM). A telecommunications network is a collection of transmitters, receivers, and communications channels that send messages to one another. Some digital communications networks contain one or more routers that work together to transmit information to the correct user. An analogue communications network consists of one or more switches that establish

2120-631: A sale-leaseback agreement valued at $ 650.3 million on the complex with the address previously known as One Verizon Way. In 2017, the 35 acre hotel/conference center was known as the Dolce Basking Ridge Hotel and sold for $ 30 million. On February 15, 2024, AT&T Inc. filed notice with the Kentucky Public Service Commission that it intends to make an internal structural change and merge AT&T Corp. into AT&T Enterprises, Inc., which will become

2226-475: A service that operated for a year until the gap in the telegraph link was closed. In the Middle Ages, chains of beacons were commonly used on hilltops as a means of relaying a signal. Beacon chains suffered the drawback that they could only pass a single bit of information, so the meaning of the message such as "the enemy has been sighted" had to be agreed upon in advance. One notable instance of their use

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2332-442: A single medium to transmit several concurrent communication sessions . Several methods of long-distance communication before the modern era used sounds like coded drumbeats , the blowing of horns , and whistles . Long-distance technologies invented during the 20th and 21st centuries generally use electric power, and include the telegraph , telephone , television , and radio . Early telecommunication networks used metal wires as

2438-411: A telephone network, the caller is connected to the person to whom they wish to talk by switches at various telephone exchanges . The switches form an electrical connection between the two users and the setting of these switches is determined electronically when the caller dials the number. Once the connection is made, the caller's voice is transformed to an electrical signal using a small microphone in

2544-412: A version of the electrical telegraph that he unsuccessfully demonstrated on September 2, 1837. His code was an important advance over Wheatstone's signaling method. The first transatlantic telegraph cable was successfully completed on July 27, 1866, allowing transatlantic telecommunication for the first time. The conventional telephone was patented by Alexander Bell in 1876. Elisha Gray also filed

2650-581: Is adapted from the French, because its written use was recorded in 1904 by the French engineer and novelist Édouard Estaunié . Communication was first used as an English word in the late 14th century. It comes from Old French comunicacion (14c., Modern French communication), from Latin communicationem (nominative communication), noun of action from past participle stem of communicare, "to share, divide out; communicate, impart, inform; join, unite, participate in," literally, "to make common", from communis". At

2756-671: Is called point-to-point communication because it occurs between a transmitter and a receiver. Telecommunication through radio broadcasts is called broadcast communication because it occurs between a powerful transmitter and numerous low-power but sensitive radio receivers. Telecommunications in which multiple transmitters and multiple receivers have been designed to cooperate and share the same physical channel are called multiplex systems . The sharing of physical channels using multiplexing often results in significant cost reduction. Multiplexed systems are laid out in telecommunication networks and multiplexed signals are switched at nodes through to

2862-451: Is called (in the jargon of the field) " quadrature amplitude modulation " (QAM) that are used in high-capacity digital radio communication systems. Modulation can also be used to transmit the information of low-frequency analogue signals at higher frequencies. This is helpful because low-frequency analogue signals cannot be effectively transmitted over free space. Hence the information from a low-frequency analogue signal must be impressed into

2968-619: Is called a "hypostyle hall", with full-bodied Doric columns modeled on the Parthenon, marking out a grid. Bosworth was seeking to coordinate the classical tradition with the requirements of a modern building. Columns were not merely the decorative elements they had become in the hands of other architects but created all the illusion of being real supports. Bosworth also designed the campus of MIT as well as Theodore N. Vail 's mansion in Morristown, New Jersey . In 1978, AT&T commissioned

3074-434: Is commonly called "keying" —a term derived from the older use of Morse Code in telecommunications—and several keying techniques exist (these include phase-shift keying , frequency-shift keying , and amplitude-shift keying ). The " Bluetooth " system, for example, uses phase-shift keying to exchange information between various devices. In addition, there are combinations of phase-shift keying and amplitude-shift keying which

3180-794: Is converted from electricity to sound. Telecommunication systems are occasionally "duplex" (two-way systems) with a single box of electronics working as both the transmitter and a receiver, or a transceiver (e.g., a mobile phone ). The transmission electronics and the receiver electronics within a transceiver are quite independent of one another. This can be explained by the fact that radio transmitters contain power amplifiers that operate with electrical powers measured in watts or kilowatts, but radio receivers deal with radio powers measured in microwatts or nanowatts . Hence, transceivers have to be carefully designed and built to isolate their high-power circuitry and their low-power circuitry from each other to avoid interference. Telecommunication over fixed lines

3286-481: Is degraded by undesirable noise . Commonly, the noise in a communication system can be expressed as adding or subtracting from the desirable signal via a random process . This form of noise is called additive noise , with the understanding that the noise can be negative or positive at different instances. Unless the additive noise disturbance exceeds a certain threshold, the information contained in digital signals will remain intact. Their resistance to noise represents

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3392-609: Is self-evident in the case of online retailer Amazon.com but, according to academic Edward Lenert, even the conventional retailer Walmart has benefited from better telecommunication infrastructure compared to its competitors. In cities throughout the world, home owners use their telephones to order and arrange a variety of home services ranging from pizza deliveries to electricians. Even relatively poor communities have been noted to use telecommunication to their advantage. In Bangladesh 's Narsingdi District , isolated villagers use cellular phones to speak directly to wholesalers and arrange

3498-448: Is separated from its adjacent stations by 200 kHz, and the difference between 200 kHz and 180 kHz (20 kHz) is an engineering allowance for the imperfections in the communication system. In the example above, the "free space channel" has been divided into communications channels according to frequencies , and each channel is assigned a separate frequency bandwidth in which to broadcast radio waves. This system of dividing

3604-449: Is the informational equivalent of two newspaper pages per person per day in 1986, and six entire newspapers per person per day by 2007. Given this growth, telecommunications play an increasingly important role in the world economy and the global telecommunications industry was about a $ 4.7 trillion sector in 2012. The service revenue of the global telecommunications industry was estimated to be $ 1.5 trillion in 2010, corresponding to 2.4% of

3710-569: Is the transmission of information with an immediacy comparable to face-to-face communication. As such, slow communications technologies like postal mail and pneumatic tubes are excluded from the definition. Many transmission media have been used for telecommunications throughout history, from smoke signals , beacons , semaphore telegraphs , signal flags , and optical heliographs to wires and empty space made to carry electromagnetic signals. These paths of transmission may be divided into communication channels for multiplexing , allowing for

3816-773: The Nipkow disk by Paul Nipkow and thus became known as the mechanical television . It formed the basis of experimental broadcasts done by the British Broadcasting Corporation beginning on 30 September 1929. However, for most of the 20th century, televisions depended on the cathode ray tube invented by Karl Ferdinand Braun . The first version of such a television to show promise was produced by Philo Farnsworth and demonstrated to his family on 7 September 1927. After World War II, interrupted experiments resumed and television became an important home entertainment broadcast medium. The type of device known as

3922-583: The POSIX operating system specifications; it added Window Manager, ADA Language and more. Issue 4 (XPG4) was published in July 1992. The Single UNIX Specification was based on the XPG4 standard. The XPG3 and XPG4 standards define all aspects of the operating system, programming languages and protocols which compliant systems should have. Multiple levels of compliance and corresponding labels were available, depending on

4028-601: The Single UNIX Specification , which was drawn from XPG4 Base and other sources. In 1996, X/Open merged with the Open Software Foundation to form The Open Group . X/Open was also responsible for the XA protocol for heterogeneous distributed transaction processing, which was released in 1991. X/Open published its specifications under the name X/Open Portability Guide (or XPG). Based on

4134-440: The spark gap transmitter for radio or mechanical computers for computing, it was the invention of the thermionic vacuum tube that made these technologies widespread and practical, leading to the creation of electronics . In the 1940s, the invention of semiconductor devices made it possible to produce solid-state devices, which are smaller, cheaper, and more efficient, reliable, and durable than thermionic tubes. Starting in

4240-705: The 1932 Plenipotentiary Telegraph Conference and the International Radiotelegraph Conference in Madrid, the two organizations merged to form the International Telecommunication Union (ITU). They defined telecommunication as "any telegraphic or telephonic communication of signs, signals, writing, facsimiles and sounds of any kind, by wire, wireless or other systems or processes of electric signaling or visual signaling (semaphores)." The definition

4346-497: The 1970s. In the 1960s, Paul Baran and, independently, Donald Davies started to investigate packet switching , a technology that sends a message in portions to its destination asynchronously without passing it through a centralized mainframe . A four-node network emerged on 5 December 1969, constituting the beginnings of the ARPANET , which by 1981 had grown to 213 nodes . ARPANET eventually merged with other networks to form

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4452-463: The AT&;T System V Interface Definition , the guide has a wider scope than POSIX , which is only concerned with direct operating system interfaces. The guide specifies a Common Application Environment (CAE) intended to allow portability of applications across operating systems. The primary aim was compatibility between different vendors' implementations of UNIX , though some vendors also implemented

4558-466: The ITU was able to compile an index that measures the overall ability of citizens to access and use information and communication technologies. Using this measure, Sweden, Denmark and Iceland received the highest ranking while the African countries Niger , Burkina Faso and Mali received the lowest. Telecommunication has played a significant role in social relationships. Nevertheless, devices like

4664-744: The Internet. While Internet development was a focus of the Internet Engineering Task Force (IETF) who published a series of Request for Comments documents, other networking advancements occurred in industrial laboratories , such as the local area network (LAN) developments of Ethernet (1983), Token Ring (1984) and Star network topology. The effective capacity to exchange information worldwide through two-way telecommunication networks grew from 281 petabytes (PB) of optimally compressed information in 1986 to 471 PB in 1993 to 2.2 exabytes (EB) in 2000 to 65 EB in 2007. This

4770-477: The Rockefeller mansion north of Tarrytown, New York , it was a modern steel structure clad top to bottom in a Greek-styled exterior, the three-story-high Ionic columns of Vermont granite forming eight registers over a Doric base. The lobby of the AT&T Building was one of the most unusual ones of the era. Instead of a large double-high space, similar to the nearby Woolworth Building , Bosworth designed what

4876-506: The United Kingdom had used the service to coordinate social arrangements and 42% to flirt. In cultural terms, telecommunication has increased the public's ability to access music and film. With television, people can watch films they have not seen before in their own home without having to travel to the video store or cinema. With radio and the Internet, people can listen to music they have not heard before without having to travel to

4982-797: The United States was spent on media that depend upon telecommunication. Many countries have enacted legislation which conforms to the International Telecommunication Regulations established by the International Telecommunication Union (ITU), which is the "leading UN agency for information and communication technology issues". In 1947, at the Atlantic City Conference, the ITU decided to "afford international protection to all frequencies registered in

5088-588: The building until it was sold in 2013. In 1969, AT&T began plans to construct an administration corporate complex in the suburbs. In early 1970, AT&T began purchases of land in the suburbs of New Jersey for this office complex and began construction in 1974. The award-winning architect, Vincent Kling , designed a Fordism style, luxurious "Pagoda" campus layout and the construction firms: New York–based Walter Kidde and Newark, New Jersey –based Frank Briscoe, managed this joint venture construction project with Vollers Construction of Branchburg, New Jersey , as

5194-467: The company's breakup in 1984. Throughout most of the 20th century, AT&T held a semi-monopoly on phone service in the United States and Canada through a network of companies called the Bell System . At this time, the company was nicknamed Ma Bell . AT&T had a domestic and global presence in laying the infrastructure of undersea routes for telecommunications. In 1950, the U.S. Navy commissioned

5300-578: The corporate logo designed by Saul Bass in 1983 and originally used by AT&T Information Systems , was created because part of the United States v. AT&T settlement required AT&T to relinquish all claims to the use of Bell System trademarks. It has been nicknamed the " Death Star " in reference to the Death Star space station in Star Wars which the logo resembles. In 1999 it

5406-437: The correct destination terminal receiver. Communications can be encoded as analogue or digital signals , which may in turn be carried by analogue or digital communication systems. Analogue signals vary continuously with respect to the information, while digital signals encode information as a set of discrete values (e.g., a set of ones and zeroes). During propagation and reception, information contained in analogue signals

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5512-491: The demand for wired services. It established station WEAF in New York as what was termed a toll station . AT&T could provide no programming, but anyone who wished to broadcast a message could pay a "toll" to AT&T and then air the message publicly. The original studio was the size of a telephone booth. The idea, however, did not take hold, because people would pay to broadcast messages only if they were sure that someone

5618-519: The development of optical fibre. The Internet , a technology independent of any given medium, has provided global access to services for individual users and further reduced location and time limitations on communications. Telecommunication is a compound noun of the Greek prefix tele- (τῆλε), meaning distant , far off , or afar , and the Latin verb communicare , meaning to share . Its modern use

5724-537: The device—from the cathode to the anode. Adding one or more control grids within the tube enables the current between the cathode and anode to be controlled by the voltage on the grid or grids. These devices became a key component of electronic circuits for the first half of the 20th century and were crucial to the development of radio, television, radar, sound recording and reproduction , long-distance telephone networks, and analogue and early digital computers . While some applications had used earlier technologies such as

5830-422: The electrical telegraph, the last commercial line was abandoned in 1880. On July 25, 1837, the first commercial electrical telegraph was demonstrated by English inventor Sir William Fothergill Cooke and English scientist Sir Charles Wheatstone . Both inventors viewed their device as "an improvement to the [existing] electromagnetic telegraph" and not as a new device. Samuel Morse independently developed

5936-641: The existence of the nearly 140-year-old entity. The internal merger took effect on May 1, 2024. AT&T, prior to its merger with SBC Communications , had three core companies: AT&T Alascom sold service in Alaska. AT&T Communications was renamed AT&T Communications – East, Inc. and sold long-distance telephone service and operated as a CLEC outside of the borders of the Bell Operating Companies that AT&T owned. It has now been absorbed into AT&T Corp. and all but 4 of

6042-403: The expense of increasing the channel bandwidth requirement. The term "channel" has two different meanings. In one meaning, a channel is the physical medium that carries a signal between the transmitter and the receiver. Examples of this include the atmosphere for sound communications, glass optical fibres for some kinds of optical communications , coaxial cables for communications by way of

6148-549: The federal government entered into an agreement known as the Kingsbury Commitment . In the Kingsbury Commitment, AT&T and the government reached an agreement that allowed AT&T to continue operating as a telephone monopoly, subject to certain conditions, including divesting its interest in Western Union. While AT&T periodically faced scrutiny from regulators, this state of affairs continued until

6254-499: The following Monday, November 21 as " the new AT&T " and began trading under the "T" symbol on December 1. Present-day AT&T Inc. claims AT&T Corp.'s history as its own, but retains SBC's pre-2005 stock price history and corporate structure. As well, all SEC filings before 2005 are under SBC, not AT&T. From 1885 to 1910, AT&T was headquartered at 125 Milk Street in Boston. With its expansion it moved to New York City, to

6360-512: The former complex, excluding the hotel/conference room building, from Pfizer for Verizon Wireless Headquarters and consolidation of employees from Manhattan as well as other nearby New Jersey building locations. In 2007, Pfizer placed the North Maple Inn for sale. At the time, it was a four-diamond, certified hotel and conference center under IACC ("International Association of Conference Centers") designation. In 2015, Verizon performed

6466-480: The former parent company's main business was now AT&T Communications Inc. , which focused on long-distance services, and with other non-RBOC activities. AT&T acquired NCR Corporation in 1991. AT&T announced in 1995 that it would split into three companies: a manufacturing/R&D company, a computer company, and a services company. NCR , Bell Labs and AT&T Technologies were to be spun off by 1997. In preparation for its spin-off, AT&T Technologies

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6572-431: The importance of social conversations and staying connected to family and friends. Since then the role that telecommunications has played in social relations has become increasingly important. In recent years, the popularity of social networking sites has increased dramatically. These sites allow users to communicate with each other as well as post photographs, events and profiles for others to see. The profiles can list

6678-523: The innovations of products or technologies in cabling in transmission by undersea systems. In 1955, the first trans-Atlantic telephone undersea cable, TAT-1 , from North America to Europe was installed by AT&T. This installation allowed 48 telephone circuits to be used for long-distance calling. When partnering with other global Telecommunications companies, such as the French Cables de Lyon and German Felten & Guilleaume , Bell Labs provided

6784-513: The label X/Open Portability Guide but rather as CAE Specification . Nonetheless, the term X/Open Portability Guide, Issue 4 sees some use in reference to 1992 year of publication. Further X/Open publications under the label X/Open CAE Specification rather than X/Open Portability Guide : AT%26T Corporation AT&T Corporation , an abbreviation for its former name, the American Telephone and Telegraph Company ,

6890-518: The laying or repair of cabling under the subsidiary, Transoceanic Cable Ship Company. After the break-up, AT&T operated their ships under a subsidiary called AT&T Submarine Systems Inc, based in Morristown, New Jersey, until they sold six ships to Tyco International Ltd in 1997 for $ 850 million. AT&T continued to maintain their communication building facilities. Here is a list of the cable laying-ship fleet: Between 1951 and 2000, AT&T

6996-601: The location peaked to 6,000 employees in its heyday before AT&T experienced competition and downsizing. In October 2001, the Basking Ridge property was 140 acre with 2.6 million square feet and was placed for sale. Basking Ridge employee occupancy, prior to the sale were approximately 3,200 employees. In April 2002, Pharmacia Corporation purchased the complex for $ 210 million for their corporate headquarters from existing Peapack-Gladstone, New Jersey headquarters. A short time afterwards, in 2005, Verizon purchased

7102-552: The management of telecommunication and broadcasting. The history of broadcasting discusses some debates in relation to balancing conventional communication such as printing and telecommunication such as radio broadcasting. The onset of World War II brought on the first explosion of international broadcasting propaganda. Countries, their governments, insurgents, terrorists, and militiamen have all used telecommunication and broadcasting techniques to promote propaganda. Patriotic propaganda for political movements and colonization started

7208-479: The medium for transmitting signals. These networks were used for telegraphy and telephony for many decades. In the first decade of the 20th century, a revolution in wireless communication began with breakthroughs including those made in radio communications by Guglielmo Marconi , who won the 1909 Nobel Prize in Physics . Other early pioneers in electrical and electronic telecommunications include co-inventors of

7314-567: The medium into channels according to frequency is called " frequency-division multiplexing ". Another term for the same concept is " wavelength-division multiplexing ", which is more commonly used in optical communications when multiple transmitters share the same physical medium. Another way of dividing a communications medium into channels is to allocate each sender a recurring segment of time (a "time slot", for example, 20 milliseconds out of each second), and to allow each sender to send messages only within its own time slot. This method of dividing

7420-414: The medium into communication channels is called " time-division multiplexing " ( TDM ), and is used in optical fibre communication. Some radio communication systems use TDM within an allocated FDM channel. Hence, these systems use a hybrid of TDM and FDM. The shaping of a signal to convey information is known as modulation . Modulation can be used to represent a digital message as an analogue waveform. This

7526-742: The mid-1930s. In 1936, the BBC broadcast propaganda to the Arab World to partly counter similar broadcasts from Italy, which also had colonial interests in North Africa. Modern political debates in telecommunication include the reclassification of broadband Internet service as a telecommunications service (also called net neutrality ), regulation of phone spam , and expanding affordable broadband access. According to data collected by Gartner and Ars Technica sales of main consumer's telecommunication equipment worldwide in millions of units was: In

7632-540: The mid-1960s, thermionic tubes were replaced with the transistor . Thermionic tubes still have some applications for certain high-frequency amplifiers. On 11 September 1940, George Stibitz transmitted problems for his Complex Number Calculator in New York using a teletype and received the computed results back at Dartmouth College in New Hampshire . This configuration of a centralized computer ( mainframe ) with remote dumb terminals remained popular well into

7738-452: The music store. Telecommunication has also transformed the way people receive their news. A 2006 survey (right table) of slightly more than 3,000 Americans by the non-profit Pew Internet and American Life Project in the United States the majority specified television or radio over newspapers. Telecommunication has had an equally significant impact on advertising. TNS Media Intelligence reported that in 2007, 58% of advertising expenditure in

7844-400: The neighbourhood of 94.5  MHz (megahertz) while another radio station can simultaneously broadcast radio waves at frequencies in the neighbourhood of 96.1 MHz. Each radio station would transmit radio waves over a frequency bandwidth of about 180  kHz (kilohertz), centred at frequencies such as the above, which are called the "carrier frequencies" . Each station in this example

7950-410: The original 22 subsidiaries that formed AT&T Communications continue to exist. AT&T Laboratories has been integrated into AT&T Labs , formerly named SBC Laboratories . AT&T was also known as "Ma Bell" and affectionately called "Mother" by phone phreaks . During some strikes by its employees, picketers would wear T-shirts reading, "Ma Bell is a real mother." Before the break-up, there

8056-438: The original five, Philips and Nokia from Europe; AT&T, Digital, Unisys, Hewlett-Packard, IBM , NCR, Sun, Prime Computer , Apollo Computer from North America; Fujitsu , Hitachi , and NEC from Japan; plus the Open Software Foundation and Unix International . In October 1993, a planned transfer of UNIX trademark from Novell to X/Open was announced; it was finalized in 2nd quarter of 1994. In 1994, X/Open published

8162-412: The patent rights of Alexander Graham Bell after he invented the telephone system. Originally a verbal agreement, it was formalized in writing in 1875 as Bell Telephone Company . In 1880 the management of American Bell created what would become AT&T Long Lines . The project was the first of its kind to create a nationwide long-distance network with a commercially viable cost-structure. The project

8268-515: The presence or absence of an atmosphere between the two. Radio waves travel through a perfect vacuum just as easily as they travel through air, fog, clouds, or any other kind of gas. The other meaning of the term "channel" in telecommunications is seen in the phrase communications channel , which is a subdivision of a transmission medium so that it can be used to send multiple streams of information simultaneously. For example, one radio station can broadcast radio waves into free space at frequencies in

8374-709: The relationship as causal. Because of the economic benefits of good telecommunication infrastructure, there is increasing worry about the inequitable access to telecommunication services amongst various countries of the world—this is known as the digital divide . A 2003 survey by the International Telecommunication Union (ITU) revealed that roughly a third of countries have fewer than one mobile subscription for every 20 people and one-third of countries have fewer than one land-line telephone subscription for every 20 people. In terms of Internet access, roughly half of all countries have fewer than one out of 20 people with Internet access. From this information, as well as educational data,

8480-473: The scope of the guide that was covered: Base and Plus; labels Component and Application are for SW components and applications that make use of the portability guide. Issue 1 was published as a single publication with multiple parts, ISBN   0-444-87839-4 . Issue 2 was published in multiple volumes: Issue 3 was published in multiple volumes: The XPG4 Base specification includes the following documents: The above three documents were published not under

8586-659: The specification and inspection of non Bell System cable for networks such as the TAT-2 . By the continuous undersea network installations, AT&T was a globally technology leader with the 1970 installed TAT-5 and the 1975 installed TAT-6 , achieving 720 channels and then 4000 channels for transmitting voice or data. Prior to 1963, AT&T had to charter oceanic ships, such as the CS Monarch (1945) for installations. AT&T purchased CS Long Lines in 1961 and operated it with several cable laying ships that would provide, either

8692-614: The standards on non-UNIX platforms. Issue 1 of the guide covered basic operating system interfaces, the C language, COBOL, indexed sequential file access method (ISAM) and other parts and was published in 1985. Issue 2 followed in 1987, and extended the coverage to include Internationalization, Terminal Interfaces, Inter-Process Communication, and the programming languages C , COBOL , FORTRAN , and Pascal , as well as data access interfaces for SQL and ISAM. In many cases these were profiles of existing international standards. Issue 3 (XPG3) followed in 1989, its primary focus being convergence with

8798-535: The subcontractor. The 295 North Maple Avenue and Interstate 287 location of Basking Ridge in Bernards Township , New Jersey was completed in 1975 for the AT&T General Department offices. Employees began moving, in November 1975, to the seven inter-connected building complex using 28 acre of the property. The property had a 15-acre underground parking garage with spaces for 3,900 vehicles, and included

8904-435: The superiority of one phone system and AT&T adopted the slogan "One Policy, One System, Universal Service." This would be the company's philosophy for the next 70 years. Under Vail, AT&T began buying up many of the smaller telephone companies including Western Union telegraph . These actions brought unwanted attention from antitrust regulators. Anxious to avoid action from government antitrust suits, AT&T and

9010-609: The telegraph Charles Wheatstone and Samuel Morse , numerous inventors and developers of the telephone including Antonio Meucci , Philipp Reis , Elisha Gray and Alexander Graham Bell , inventors of radio Edwin Armstrong and Lee de Forest , as well as inventors of television like Vladimir K. Zworykin , John Logie Baird and Philo Farnsworth . Since the 1960s, the proliferation of digital technologies has meant that voice communications have gradually been supplemented by data. The physical limitations of metallic media prompted

9116-412: The telephone system were originally advertised with an emphasis on the practical dimensions of the device (such as the ability to conduct business or order home services) as opposed to the social dimensions. It was not until the late 1920s and 1930s that the social dimensions of the device became a prominent theme in telephone advertisements. New promotions started appealing to consumers' emotions, stressing

9222-631: The then-newly discovered phenomenon of radio waves , demonstrating, by 1901, that they could be transmitted across the Atlantic Ocean. This was the start of wireless telegraphy by radio. On 17 December 1902, a transmission from the Marconi station in Glace Bay, Nova Scotia, Canada , became the world's first radio message to cross the Atlantic from North America. In 1904, a commercial service

9328-490: The voltages and electric currents in them, and free space for communications using visible light , infrared waves, ultraviolet light , and radio waves . Coaxial cable types are classified by RG type or "radio guide", terminology derived from World War II. The various RG designations are used to classify the specific signal transmission applications. This last channel is called the "free space channel". The sending of radio waves from one place to another has nothing to do with

9434-492: The wartime purposes of aircraft and land communication, radio navigation, and radar. Development of stereo FM broadcasting of radio began in the 1930s in the United States and the 1940s in the United Kingdom, displacing AM as the dominant commercial standard in the 1970s. On March 25, 1925, John Logie Baird demonstrated the transmission of moving pictures at the London department store Selfridges . Baird's device relied upon

9540-418: The world's gross domestic product (GDP). Modern telecommunication is founded on a series of key concepts that experienced progressive development and refinement in a period of well over a century: Telecommunication technologies may primarily be divided into wired and wireless methods. Overall, a basic telecommunication system consists of three main parts that are always present in some form or another: In

9646-405: Was acquired by " Baby Bell " and former subsidiary SBC Communications for more than $ 16 billion ($ 25 billion in present-day terms ). SBC then changed its name to AT&T Inc. , with AT&T Corporation continuing to exist as a long distance subsidiary until its dissolution on May 1, 2024. AT&T started with Bell Patent Association , a legal entity established in 1874 to protect

9752-625: Was an American telecommunications company that provided voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agencies. During the Bell System 's long history, AT&T was at times the world's largest telephone company, the world's largest cable television operator, and a regulated monopoly. At its peak in the 1950s and 1960s, it employed one million people and its revenue ranged between US$ 3 billion in 1950 ($ 41.3 billion in present-day terms ) and $ 12 billion in 1966 ($ 117 billion in present-day terms ). In 2005, AT&T

9858-464: Was because Massachusetts corporate laws were very restrictive, and limited capitalization to ten million dollars, forestalling American Bell's further growth. With this assets transfer at the very end of the 19th century, AT&T became the parent of both American Bell and the Bell System . AT&T was involved mainly in the telephone business and, although it was a partner with RCA , was reluctant to see radio grow because such growth might diminish

9964-630: Was changed from the 12-line design to the 8-line design. Again in 2005 it was changed to the 3D transparent "marble" design created by Interbrand for use by the parent company AT&T Inc. This name was also given to the iconic Bell Labs facility in Holmdel, New Jersey , now a multi-tenant office facility. The following is a list of the 16 CEOs of AT&T Corporation, from its incorporation in 1885 until its purchase by SBC Communications in 2005. Telecommunications Telecommunication , often used in its plural form or abbreviated as telecom ,

10070-490: Was during the Spanish Armada , when a beacon chain relayed a signal from Plymouth to London . In 1792, Claude Chappe , a French engineer, built the first fixed visual telegraphy system (or semaphore line ) between Lille and Paris. However semaphore suffered from the need for skilled operators and expensive towers at intervals of ten to thirty kilometres (six to nineteen miles). As a result of competition from

10176-407: Was established to transmit nightly news summaries to subscribing ships, which incorporated them into their onboard newspapers. World War I accelerated the development of radio for military communications . After the war, commercial radio AM broadcasting began in the 1920s and became an important mass medium for entertainment and news. World War II again accelerated the development of radio for

10282-542: Was formally incorporated in New York as a separate company named American Telephone and Telegraph Company on March 3, 1885. Originating in New York City, its long-distance telephone network reached Chicago, Illinois , in 1892, with its multitudes of local exchanges continuing to stretch further and further yearly, eventually creating a continent-wide telephone system. On December 30, 1899, the assets of American Bell were transferred into its subsidiary American Telephone and Telegraph Company (formerly AT&T Long Lines ); this

10388-516: Was greater consumer recognition of the "Bell System" name, in comparison to the name AT&T. This prompted the company to launch an advertising campaign after the break-up to increase its name recognition. Spinoffs like the Regional Bell Operating Companies or RBOC s were often called "Baby Bells". Ironically, "Ma Bell" was acquired by one of its "Baby Bells", SBC Communications , in 2005. The AT&T Globe Symbol,

10494-471: Was later reconfirmed, according to Article 1.3 of the ITU Radio Regulations , which defined it as "Any transmission , emission or reception of signs, signals, writings, images and sounds or intelligence of any nature by wire , radio, optical, or other electromagnetic systems". Homing pigeons have been used throughout history by different cultures. Pigeon post had Persian roots and

10600-676: Was later used by the Romans to aid their military. Frontinus claimed Julius Caesar used pigeons as messengers in his conquest of Gaul . The Greeks also conveyed the names of the victors at the Olympic Games to various cities using homing pigeons. In the early 19th century, the Dutch government used the system in Java and Sumatra . And in 1849, Paul Julius Reuter started a pigeon service to fly stock prices between Aachen and Brussels ,

10706-457: Was listed 73 times in cable laying operations for specific routes deployed. The Cable Ship Long Lines had 23 cable runs from 1963 to 1992, with the first deep-sea trial of optical fiber cable in 1982 leading to the consortium of countries and locations for the TAT-8 fiber cable implementation of 1988. The United States Justice Department opened the case United States v. AT&T in 1974. This

10812-541: Was listening. As a result, WEAF began broadcasting entertainment material, drawing amateur talent found among its employees. Opposition to AT&T's expansion into radio and an agreement with the National Broadcasting Company to lease long-distance lines for their broadcasts resulted in the sale of the station and its developing network of affiliates to NBC. On April 30, 1907, Theodore Newton Vail became President of AT&T. Vail believed in

10918-486: Was of little practical value because it relied on the electrophonic effect requiring users to place the receiver in their mouths to "hear". The first commercial telephone services were set up by the Bell Telephone Company in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven and London. In 1894, Italian inventor Guglielmo Marconi began developing a wireless communication using

11024-522: Was one of the divisions responsible for the cable-laying and maintaining of Long Lines' undersea cables. Western Electric was the manufacturing company responsible for production and supply of undersea coaxial equipment and later, fiber cables. Equipment such as repeaters was manufactured in Clark, New Jersey and coaxial cable was manufactured in Baltimore, Maryland . Also, Bell Labs was responsible for

11130-400: Was prompted by suspicion that AT&T was using monopoly profits from its Western Electric subsidiary to subsidize the cost of its network, a violation of antitrust law. A settlement to this case was finalized in 1982, leading to the division of the company on January 1, 1984, into seven Regional Bell Operating Companies , commonly known as Baby Bells. These companies were: Post-breakup,

11236-546: Was renamed Lucent Technologies . Lucent was completely spun off from AT&T in 1996. On January 31, 2005, the " Baby Bell " company SBC Communications announced its plans to acquire " Ma Bell " AT&T Corp. for $ 16 billion. SBC announced in October 2005 that it would shed the "SBC" brand and take the more recognizable AT&T brand, along with the old AT&T's "T" NYSE ticker symbol. Merger approval concluded on November 18, 2005; SBC Communications began rebranding

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