John W. Sidgmore (April 9, 1951 – December 11, 2003) was a corporate executive.
86-517: MCI, Inc. (formerly WorldCom and MCI WorldCom ) was a telecommunications company. For a time, it was the second-largest long-distance telephone company in the United States , after AT&T . WorldCom grew largely by acquiring other telecommunications companies, including MCI Communications in 1998, and filed for bankruptcy in 2002 after an accounting scandal , in which several executives, including CEO Bernard Ebbers , were convicted of
172-412: 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
258-411: 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
344-505: A $ 37 billion merger to form MCI WorldCom, making it the largest corporate merger in U.S. history. On September 15, 1998, the merger was consummated, forming MCI WorldCom . MCI divested itself of its "internetMCI" business to gain approval from the United States Department of Justice . On October 5, 1999, Sprint Corporation and MCI WorldCom announced a $ 129 billion merger. Had the deal been completed, it would have been
430-411: 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
516-438: 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
602-441: 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
688-495: 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
774-488: A formal inquiry into these matters on June 26, 2002. The SEC was already investigating WorldCom for questionable accounting practices. By the end of 2003, it was estimated that the company's total assets had been inflated by about $ 11 billion. The fraud came to light just days after Andersen was convicted of obstruction of justice in the Enron scandal, a verdict that effectively put Andersen out of business. In his post-mortem of
860-406: 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
946-450: 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
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#17327719386751032-838: 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
1118-454: A partnership with MCI to provide Windows Live Messenger customers voice over IP service to make telephone calls—called "MCI Web Calling". After the merger with Verizon, this product was renamed "Verizon Web Calling". In January 2006, the company was acquired by Verizon Communications and was later integrated into Verizon Business . Telecommunications Telecommunication , often used in its plural form or abbreviated as telecom ,
1204-437: 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
1290-491: 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
1376-499: A report for Rakoff, titled Restoring Trust, in which he proposed extensive corporate governance reforms, as part of an effort to "cast the new MCI into what he hoped would become a model of how shareholders should be protected and how companies should be run". The company emerged from bankruptcy in 2004 with about $ 5.7 billion in debt and $ 6 billion in cash. About half of the cash was intended to pay various claims and settlements. Previous bondholders ended up being paid 35.7 cents on
1462-691: A scheme to inflate the company's assets. In January 2006, the company, by then renamed MCI, was acquired by Verizon Communications and was later integrated into Verizon Business . WorldCom was originally headquartered in Clinton, Mississippi before relocating to Ashburn, Virginia when it changed its name to MCI. In 1983, in a coffee shop in Hattiesburg, Mississippi , Bernard Ebbers and three other investors formed Long Distance Discount Services, Inc. based in Jackson, Mississippi and in 1985, Ebbers
1548-678: A sentence that would have kept him imprisoned for 25 years. At time of sentencing, Ebbers was 63 years old. On September 26, 2006, Ebbers surrendered himself to the Federal Bureau of Prisons prison at Oakdale, Louisiana , the Oakdale Federal Correctional Institution , to begin serving his sentence; he was released in late 2019 for health reasons and died in February 2020, after serving 13 years of his sentence. In December 2005, Microsoft announced
1634-475: 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
1720-442: 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
1806-488: A span of eleven days during September 2008). The WorldCom bankruptcy proceedings were held before U.S. Federal Bankruptcy Judge Arthur Gonzalez , who simultaneously heard the Enron bankruptcy proceedings, which were the second-largest bankruptcy case resulting from one of the largest corporate fraud scandals. None of the criminal proceedings against WorldCom and its officers and agents were originated by referral from Gonzalez or
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#17327719386751892-411: 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
1978-412: 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
2064-581: 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
2150-671: 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
2236-451: 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
2322-434: 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
2408-794: 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
2494-481: 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
2580-609: 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
2666-448: 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
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2752-449: 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
2838-569: 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
2924-773: 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
3010-499: The U.S. Securities and Exchange Commission . The deal was approved by federal judge Jed Rakoff in July 2003. In a sweeping consent decree , the SEC and Rakoff essentially took control of WorldCom. Rakoff appointed former SEC chairman Richard C. Breeden to oversee WorldCom's compliance with the SEC agreement. Breeden actively involved himself with the management of the company, and prepared
3096-493: The board of directors of WorldCom authorized several loans and loan guarantees to CEO Bernard Ebbers so that he would not have to sell his WorldCom shares to meet margin calls as the share price plummeted during the bursting of the dot-com bubble . By April 2002, the board had lost patience with these loans. Directors also believed that Ebbers did not seem to have a coherent strategy after the Sprint merger collapsed. On April 26,
3182-486: The fraud uncovered at Enron less than a year earlier. It would remain the largest accounting fraud ever uncovered until the exposure of Bernard Madoff 's giant Ponzi scheme in 2008. By this time, the U.S. Attorney for the Southern District of Mississippi , the Federal Bureau of Investigation and the U.S. Securities and Exchange Commission were already looking into the matter as well. The SEC launched
3268-440: 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
3354-705: 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
3440-497: 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
3526-552: The Department of Justice lawyers. By the bankruptcy reorganization agreement, the company paid $ 750 million to the SEC in cash and stock in the new MCI, which was intended to be paid to wronged investors. Effective December 16, 2002, Michael Capellas became chairman and chief executive officer. On April 14, 2003, WorldCom changed its name to MCI , and relocated its corporate headquarters from Clinton, Mississippi , to Ashburn, Virginia . Even before then, however, employees from
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3612-500: The Enron scandal, Conspiracy of Fools , journalist Kurt Eichenwald argued that Andersen's failure to uncover WorldCom's deceit would have brought Andersen down even if it had escaped the Enron fraud unscathed. On July 21, 2002, WorldCom filed for Chapter 11 bankruptcy protection in the largest such filing in United States history at the time (overtaken by the bankruptcies of both Lehman Brothers and Washington Mutual in
3698-466: 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
3784-744: 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
3870-619: The MCI side of the merger had taken over top executive posts, while many longtime executives from the old WorldCom were pushed out. In late 2002, the company began moving most of its operations to its campus in Ashburn, which had opened in 2000. Capellas, for instance, spent most of his time in Northern Virginia. After the name change, one executive from the old MCI said, "We're taking our company back." Another wrote in an email, "My company
3956-506: 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
4042-734: 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
4128-647: The board voted to ask for Ebbers' resignation. Ebbers formally resigned on April 30, 2002 and was replaced by John W. Sidgmore , former CEO of UUNET . As part of his departure, Ebbers's loans were consolidated into a single $ 408.2 million promissory note . In 2003, Ebbers defaulted on the note and WorldCom foreclosed on many of his assets. Beginning modestly during mid-1999 and continuing at an accelerated pace through May 2002, Ebbers, CFO Scott Sullivan , controller David Myers and general accounting director Buford "Buddy" Yates used fraudulent accounting methods to disguise WorldCom's decreasing earnings in order to maintain
4214-659: The caller's handset . This electrical signal is then sent through the network to the user at the other end where it is transformed back into sound by a small speaker in that person's handset. John W. Sidgmore He became the Chief Executive Officer of UUNET Technologies in June 1994. UUNET was purchased by MFS , later taken over by WorldCom , which eventually bought MCI . He later became WorldCom's Chief Operations Officer. Sidgmore worked to revive WorldCom after disgraced CEO Bernard Ebbers left. Sidgmore
4300-471: The company's stock price. The fraud was accomplished primarily in two ways: In June 2002, a small team of internal auditors at WorldCom led by division vice president Cynthia Cooper and senior associate Eugene Morse worked together, often at night and secretly, to investigate and reveal what was ultimately discovered to be $ 3.8 billion worth of fraudulent entries in WorldCom's books. The investigation
4386-437: 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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#17327719386754472-519: 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
4558-537: 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
4644-608: The dollar, in bonds and stock in the new MCI company. The previous stockholders' stock was cancelled. It had yet to pay many of its creditors, who had waited for two years for a portion of the money owed. Many of the small creditors included former employees, primarily those who were dismissed during June 2002 and whose severance and benefits were withheld when WorldCom filed for bankruptcy. Citigroup settled with Worldcom investors for $ 2.65 billion on May 10, 2004. In March 2007, 16 of WorldCom's 17 former underwriters reached settlements with investors. On March 15, 2005, Bernard Ebbers
4730-422: 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
4816-403: 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
4902-431: 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
4988-546: The largest corporate merger in history. The merged company would have surpassed AT&T as the largest communications company in the United States. However, the deal floundered due to opposition from the U.S. Department of Justice and the European Union on concerns that it would create a monopoly. On July 13, 2000, the boards of directors of both companies terminated the merger. Later that year, MCI WorldCom renamed itself "WorldCom". Between September 2000 and April 2002,
5074-552: 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
5160-479: 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
5246-567: 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
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#17327719386755332-414: 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
5418-589: The merger with WorldCom. In February 1998, WorldCom acquired CompuServe from its parent company H&R Block . WorldCom then retained the CompuServe Network Services Division, sold its online service to America Online , and received AOL's network division, ANS. WorldCom acquired the corporate parent of Digex , Intermedia Communications in June 2001 and then sold all of Intermedia's non-Digex assets to Allegiance Telecom. On November 4, 1997, WorldCom and MCI Communications announced
5504-742: 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
5590-596: 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
5676-452: 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
5762-400: 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
5848-515: 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
5934-709: 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,
6020-609: 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
6106-412: 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
6192-631: 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
6278-490: 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
6364-492: 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
6450-418: 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
6536-490: 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
6622-407: 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
6708-911: Was found guilty of all charges and convicted of fraud, conspiracy and filing false documents with regulators—all related to the $ 11 billion accounting scandal. Other former WorldCom officials charged with criminal penalties in relation to the company's financial misstatements include former CFO Scott Sullivan (entered a guilty plea on March 2, 2004, to one count each of securities fraud, conspiracy to commit securities fraud, and filing false statements), former controller David Myers (pleaded guilty to securities fraud, conspiracy to commit securities fraud, and filing false statements on September 27, 2002), former accounting director Buford Yates (pleaded guilty to conspiracy and fraud charges on October 7, 2002), and former accounting managers Betty Vinson and Troy Normand (both pleading guilty to conspiracy and securities fraud on October 10, 2002). On July 13, 2005, Bernard Ebbers received
6794-574: Was in 1992 with the $ 720 million acquisition of Advanced Telecommunications Corporation, outbidding larger rivals Sprint Corporation and AT&T to secure the deal, making WorldCom a larger player in the telecoms market. Other acquisitions included: Metromedia Communication Corp. and Resurgens Communications Group in 1993, IDB Communications Group, Inc (1994), Williams Technology Group, Inc. (1995), and MFS Communications Company (1996), and MCI in 1998. The acquisition of MFS included UUNET Technologies, Inc., which had been acquired by MFS shortly before
6880-551: Was instrumental in beginning to turn around the failed company, revealing to federal investigators an $ 11 billion accounting fraud, left over from Ebbers' management of the company. John Sidgmore died suddenly on December 11, 2003, at the age of 52 from kidney failure . He is survived by his wife Randi, and their son, Michael. A native of Spring Valley, New York , he attended the State University of New York at Oneonta , majoring in economics. This article about
6966-471: 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
7052-676: 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 ,
7138-458: Was named chief executive officer . The company acquired over 60 telecommunications firms, and in 1995, it changed its name to WorldCom. In 1989, it became a corporation as a result of a merger with Advantage Companies Inc. The company name was changed to LDDS WorldCom in 1995, and it relocated to Clinton, Mississippi . The company grew rapidly in the 1990s, after completing several mergers and acquisitions . WorldCom's first major acquisition
7224-476: Was not founded in a motel coffee shop." In May 2003, in a controversial deal, the company was given a $ 45 million no-bid contract by the United States Department of Defense to build a cellular phone service in Iraq as part of the U.S.-led reconstruction effort despite the fact that the company was not known for its expertise in building wireless networks. WorldCom agreed to pay a civil penalty of $ 2.25 billion to
7310-486: 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
7396-487: Was triggered by suspicious balance sheet entries discovered during a routine capital expenditure audit. Cooper notified the company's audit committee and board of directors in June 2002. The board moved swiftly, forcing Myers to resign and firing Sullivan when he refused to resign. Arthur Andersen withdrew its audit opinion for 2001. Cooper and her team had exposed the largest accounting fraud in American history, displacing
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