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Telecommunications

Telecommunications refer to the transmission of information over distances for the purpose of communication. In the modern age of electronics and electricity, telecommunication includes the use of electrical devices, radio and microwave communications, fiber optics, orbiting satellites and the Internet.

2,044 Questions

Where did the telephone get its name?

The cell phone got its name from the word cellular. Cell is the generic industry term. The word cell itself was given due to the physical appearance of the actual cell site installations that resemble a honeycomb shape.

Where did Morse code come from?

The land telegraph was invented by Samuel F. B. Morse, in the 1830s I think. He built this thing that when a button was pushed at one place, it could cause a clacker to go clack at the other end of a wire many miles long. In order to send information over it, he invented a code of clacks for each letter of the alphabet ... which he modestly called Morse's Code.

What did the telephone do or say?

The first telephone is used as what is the use of today. But today's telephone are more and more useful because for example, you can connect a local virtual number to a primary number to create presence in any city of your choice.

What are the seven standards systems development life cycle phases?

Stages of SDLC are: 1) Plan

2) Analyze

3) Design

4) Produce

5) Validate

6) Implement
There are various stages involved in developing a software , But generally a software is made by programming and the program by which is divided into different modules , Each carrying a function on its own,

These are the steps in brief :

*Analyzing or Understanding your software needs (i.e. Wat your end output is)

*Writing the pseudocode or the skeleton of the program for the software

*Drawing Relevant Flowcharts for the pseudocode

*Coding the programs by splitting into different sub modules

*Debugging any minor bugs in the coding by running tests

*Testing the Final Verified coding

*Designing Interfaces and producing a output with the alpha or the first prototype of the software

*Finally preparing documentation, Marketing , claiming copyrights

What are the Components of telecommunication network?

A small business telephone systems may often include the following components: -The PBX’s internal switching network -Microcontroller or microcomputer for arbitrary data processing, control and logic -Logic cards, switching and control cards, power cards and related devices that facilitate PBX operation -Stations or telephone sets, sometimes called lines -Outside Telco trunks that deliver signals to (and carry them from) the PBX -Console or switchboard allows the operator to control incoming calls -Uninterruptible Power Supply (UPS) consisting of sensors, power switches and batteries -Interconnecting wiring -Cabinets, closets, vaults and other housings

How do you read a telegraph?

What ever it says then that how you read it. it's translated for you.

Did the Morse code use dots and dashes to send messages over wires?

Actually Morse's original code used dots, dashes, long dashes, and very long dashes. It also used 5 different lengths of gaps.

This was greatly simplified by the adoption of the International Morse code (largely developed in Germany then modified a bit by international agreements) to just dots and dashes. The number of different length gaps was also reduced to only 3.

What did the victorians use the telephone for?

It was important because they needed a way of contacting people when they were away and in other places of the world.The Victorians made it clear that the telephone was the greatest and best way of cantacting people and they were very pleased with Alexander Graham Bell who invented it. Now the Victorian telephone has been updated and is very good and works better but in those times they did not have to pay.

The inventor, Alexander Graham Bell, was born in Edinburgh, Scotland in 1847.

What is attenuation in communication?

loss of signal strength as distance increases The reduction of signal energy during transmission.

What is the dsl technology?

Verizon FiOS es un servicio de comunicaciones integradas que opera en una red de fibra óptica, ofrecido en algunas áreas de Estados Unidos por Verizon. Verizon atrajo la atención de los consumidores y los medios en el área del ADSL al ser el primer operador de los Estados Unidos en ofrecer Fibra Óptica a los hogares

yazing . com / deals / verizon / adrian 33

What song is played in the ATT commercial where the guy sends pictures to the girl?

Lenny Spinella of Malden, MA sings that song. Gene Wilder originally sang that song years ago, but Lenny did the remake!

No, that's not the one with the orange scrolls. The one with the orange scrolls is called "From the Morning" by Nick Drake.

What are the risks and controls in Telephone banking?

Unauthorized access or Phishing is one of the main risks in Internet Banking. If a customer provides his internet banking credentials in a website that is not a legit bank website, his details can be used by the fake website to access his bank account and make transactions.

To control this - customers should be educated about phishing and asked to validate the authenticity of the website before they enter their credentials. Also customers must keep their credentials memorized and if they have written it down, they must keep it in a safe place that can be accessed only by themselves.

Do you have to have internet for all ATT smartphones?

This article is about the company known as AT&T since 2005. For the original AT&T, see AT&T Corporation. For other uses, see AT&T (disambiguation).

AT&T Inc. Type Public Traded as NYSE: T
BMV: T
FWB: SOBA
Dow Jones Component
S&P 500 Component
Industry Telecommunications Predecessor(s) American Telephone and Telegraph Company Founded October 5, 1983[1]Headquarters Whitacre Tower, Downtown,
Dallas, Texas, United States Key people Randall Stephenson
(Chairman, President & CEO)[2]Services Fixed line and mobile telephony, broadband and fixed-line internet services,digital television Revenue US$ 124.280 billion (2010)[3]Operating income US$ 19.573 billion (2010)[3]Net income US$ 19.864 billion (2010)[3]Total assets US$ 277.653 billion (2011)[3]Total equity US$ 111.950 billion (2010)[3]Employees 294,600 (2010)[3]Parent AT&T Corp. (1983) Subsidiaries AT&T Corp.
AT&T Mobility
BellSouth
Southwestern Bell
AT&T Teleholdings Website ATT.com

Whitacre Tower: AT&T's corporate headquarters in Dallas, Texas

AT&T Inc. (sometimes stylized as at&t; NYSE: T, for "telephone") is an American multinational telecommunications corporation headquartered in Whitacre Tower, Dallas, Texas, United States. It is the second largest provider of mobile telephony and fixed telephony in the United States, and is also a provider of broadband and subscription television services. As of 2010, AT&T is the 7th largest company in the United States by total revenue, as well as the 4th largest non-oil company in the US (behind Walmart, General Electric, and Bank of America). It is the 3rd largest company in Texas by total revenue (behindExxonMobiland ConocoPhillips) and the largest non-oil company in Texas. It is also the largest company headquartered in Dallas.[4]In 2011, Forbes listed AT&T as the 14th largest company in the world by market value[5]and the 9th largest non-oil company in the world by market value.[6]It is the 20th largest mobile telecom operator in the world with over 100.7 million mobile customers.[7]

The company began its existence as Southwestern Bell Corporation, one of seven Regional Bell Operating Companies created in 1983 as part of the break-up of the original AT&T due to the United States v. AT&T antitrust lawsuit. It changed its name to SBC Communications Inc. in 1995. In 2005, it purchased its former parent company, AT&T Corporation (originally known as the American Telephone and Telegraph Company), and took on its branding, with the merged entity naming itself AT&T Inc. and using the iconic AT&T logo and stock-trading symbol.

The current AT&T reconstitutes much of the former Bell System and includes ten of the original 22 Bell Operating Companies, along with one it partially owned (Southern New England Telephone), and the original long distance division.[8]The company is headquartered in downtown Dallas, Texas.[9]

Contents[hide] [edit]History[edit]1984-2001: Southwestern Bell Corporation

American Telephone and Telegraph Company officially transferred full ownership of Southwestern Bell Telephone Company to Southwestern Bell Corporation on January 1, 1984. It had three other subsidiaries: Southwestern Bell Publications, Inc., a directory publisher; Southwestern Bell Mobile Systems, Inc., in the business of mobile telephone service; and Southwestern Bell Telecommunications, Inc., focusing on marketing phone equipment to business customers. The holding companies' new president was Zane Edison Barnes.

Southwestern Bell Corporation logo, 1992-1995

In 1987, SBC bought Metromedia Inc.'s cellular and paging business. This in turn boosted the company to third largest cellular-communications company in the United States; behind McCaw Cellular and Pacific Telesis. In January 1990, Edward Whitacre took over as president of Southwestern Bell. The Headquarters was moved from St. Louis to San Antonio, Texas in February 1993. It acquired 2 cable companies in Maryland and Virginiafrom Hauser Communications for $650 million, becoming the first regional Bell telephone company to acquire a cable company outside of its service area. In 1994, they called off a $1.6 billion acquisition attempt for 40% ofCox Cable due to FCC rules on cable companies. SBC would later start selling its current cable company interests.

[edit]1995-2000: Changes in the company

SBC Communications logo, 2001-2005

In 1995 Southwestern Bell Corp. became SBC Communications. They then combined Southwestern Bell Telecom division (which made telephone equipment) into the company, due to new FCC rules.

In 1996, SBC announced it would acquire Pacific Telesis Group, a Regional Bell Operating Company (RBOC) in California and Nevada. 1997 brought rumors of a proposed merger between AT&T Corporation (the USA's largest long distance provider) and SBC (the USA's largest local provider). The FCC disapproved of the merger, and it came to end. Later in 1997, SBC sold its last two cable companies, exiting the cable telecom field.

In January 1998, SBC announced it would take over Southern New England Telecommunications Corp. (SNET) for $4.4 billion in stock (the FCC would approve in October 1998). SBC also won a court judgment that would make it easier for RBOCs to enter the long distance phone service, but it was being challenged by AT&T and the FCC. In May 1998, Ameritech and SBC announced a $62 billion dollar merger, in which SBC would take over Ameritech. After making several organizational changes (such as the sale of Ameritech Wireless to GTE) to satisfy state and federal regulators, the two merged on October 8, 1999. The FCC later fined SBC Communications $6 million for failure to comply with agreements made in order to secure approval of the merger. SBC became the largest RBOC until the Bell Atlantic and GTE merger. 1998 revenues were $46 billion, placing SBC among the top 15 companies in the Fortune 500.

In January 1999, SBC announced it would purchase Comcast Cellular, for $1.7 billion, plus $1.3 billion of debt. During 1999 SBC continued to prepare to be allowed to provide long distance phone service. February SBC acquired up to ten percent of Williams Companies' telecommunications division for about $500 million, who was building a fiber optic network across the country and would carry SBC's future service. On November 1, 1999, SBC became a part of the Dow Jones Industrial Average.

[edit]2000-2005: One national brand, and acquisition of AT&T Corporation

This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.(February 2010)

The final AT&T logo prior to its merger with SBC in late 2005.

In 2002, SBC ended marketing its operating companies under different names, and simply opted to give its companies different doing business as names based on the state (a practice already in use by Ameritech since 1993), and it gave the holding companies it had purchased d/b/a names based on their general region.

SBC-AT&T legacy transition logo, used 2005-2006

On January 31, 2005, SBC announced that it would purchase AT&T Corporation for more than US$16 billion. The announcement came almost eight years after SBC and AT&T (originally known as the American Telephone and Telegraph Company) called off their first merger talks and nearly a year after initial merger talks between AT&T Corp. andBellSouthfell apart. AT&T stockholders meeting in Denver, approved the merger on June 30, 2005. The U.S. Department of Justice cleared the merger on October 27, 2005, and the Federal Communications Commission approved it on October 31, 2005.

The merger was finalized on November 18, 2005.[10]Upon the completion of the merger, SBC Communications adopted the AT&T branding, and changed its corporate name toAT&T Inc. to differentiate the company from the former AT&T Corporation. On December 1, 2005, the merged company's New York Stock Exchange ticker symbol was changed from "SBC" to the traditional "T" used by AT&T.

The new AT&T updated the former AT&T's graphic logo (a new "marble" designed by Interbrand took over the "Death Star"); however the existing AT&T sound trademark (voiced by Pat Fleet) continues to be used.

[edit]2006: BellSouth acquisition

The BellSouth logo.

On Friday December 29, 2006, the Federal Communications Commission (FCC) approved the new AT&T's acquisition of a regional Bell Operating Company, BellSouth, valued at approximately $86 billion (or 1.325 shares of AT&T for each share of BellSouth at the close of trading December 29, 2006).[11]The new combined company retained the name AT&T.[12]The deal consolidated ownership of both Cingular Wireless andYellowpages.com, once joint ventures between BellSouth and AT&T. All services, including wireless, became offered under the AT&T name.[13]

[edit]2007-2008 restructuring[edit]Transition to new media

The AT&T Switching Center in downtown Los Angeles.

In June 2007, AT&T's new chairman and CEO, Randall Stephenson, discussed how wireless services are the core of "The New AT&T".[14]With declining sales of traditional home phone lines, AT&T plans to roll out various new media such as Video Share, U-verse, and to extend its reach in high speed Internet into rural areas across the country. AT&T announced on June 29, 2007, however, that it was acquiring Dobson Communications. It was then reported on October 2, 2007 that AT&T would purchase Interwise[clarification needed] for $121 million, which it completed on November 2, 2007. On October 9, 2007, AT&T purchased 12 MHz of spectrum in the prime 700 MHz spectrum band from privately held Aloha Partners for nearly $2.5 billion; the deal was approved by the FCC on February 4, 2008. On December 4, 2007 AT&T announced plans to acquire Edge Wireless, a regional GSM carrier in the Pacific Northwest.[15]The Edge Wireless acquisition was completed in April 2008.[16]

[edit]Corporate headquarters move

On June 27, 2008, AT&T announced that it would move its corporate headquarters from 175 East Houston Street in San Antonio to One AT&T Plaza in Downtown Dallas.[9][17]The company said that it moved to gain better access to its customers and operations throughout the world, and to the key technology partners, suppliers, innovation and human resources needed as it continues to grow, domestically and internationally[18]

AT&T Inc. previously relocated its corporate headquarters to San Antonio from St. Louis in 1992, when it was then named Southwestern Bell Corporation. The company's Telecom Operations group, which serves residential and regional business customers in 22 U.S. states, remains in San Antonio.[citation needed]

Atlanta continues to be the headquarters for AT&T Mobility, with significant offices in Redmond, Washington, the former home of AT&T Wireless. Bedminster, New Jersey is the headquarters for the company's Global Business Services group and AT&T Labs. St. Louis continues as home to the company's Directory operations, AT&T Advertising Solutions.[19]

[edit]Job cuts

On December 4, 2008, AT&T announced they would be cutting 12,000 jobs due to "economic pressures, a changing business mix and a more streamlined organizational structure".[20]

[edit]Post-consolidation wireless acquisitions[edit]Cellular One acquisition

On June 29, 2007 AT&T announced that they had reached an agreement to purchase Dobson Cellular, which provided services in the US under the name Cellular One in primarily rural areas. The closing price was $2.8B USD, or $13 per share. AT&T also agreed to assume the outstanding debt of $2.3B USD. The sale completed on November 15, 2007, with market transition beginning December 9, 2007.[21]

[edit]Centennial acquisition

On November 11, 2008, AT&T announced a $944 million buyout of Centennial Communications Corp. The acquisition is subject to regulatory approval, the approval of Centennial's stockholders and other customary closing conditions. Welsh, Carson, Anderson & Stowe, Centennial's largest stockholder, has agreed to vote in support of this transaction. In an attempt to quell regulators, on May 9, 2009 AT&T entered an agreement with Verizon Wireless to sell off certain existing Centennial service areas in the states of Louisiana and Mississippi for $240 million pending the successful merger of AT&T and Centennial.[22]

[edit]Wayport acquisition

On December 12, 2008, AT&T acquired Wayport, Inc., a major provider of Internet hotspots in the United States. With the acquisition, AT&T's public Wi-Fi deployment climbed to 20,000 hotspots in the United States, the most of any U.S. provider.[23]

[edit]Qualcomm spectrum

On December 20, 2011, AT&T and Qualcomm announced that AT&T would buy $1.93 billion worth of spectrum from Qualcomm. Formerly used for FLO TV, this spectrum will be used to expand AT&T's 4G wireless services. AT&T already had spectrum for the purpose close to what it is buying.[24]

[edit]Attempted acquisition of T-Mobile USAMain article: Attempted purchase of T-Mobile USA by AT&T

On March 20, 2011, AT&T announced its intention to buy T-Mobile USA for $39 billion from Deutsche Telekom. The deal comes with 33.7 million subscribers, making AT&T the largest mobile phone company in the United States.[25][26]If the deal goes through AT&T would have a 43% market share of mobile phones in the U.S. making AT&T significantly larger than any of its competitors. Regulators question the effects such a deal will have on both competitors and consumers.[25]AT&T CEO Randall Stephenson however stated that the merger would increase network quality and would lead to large savings for the company. AT&T stated it may have to sell some assets to gain approval from regulators, but claims to have done their "homework" on regulations.[27]

Reaction to the announced merger has generated both support as well as opposition among various groups and communities.

The merger has garnered support from a wide number of civil rights, environmental, and business organizations. These include the NAACP, League of United Latin American Citizens, Gay & Lesbian Alliance Against Defamation (GLAAD), League of United Latin American Citizens (LULAC), and the Sierra Club.[28]Labor organizations such as the AFL-CIO, Teamsters, and the Communications Workers of America also voiced support for the merger. These organizations point to AT&T's commitment to labor, social, and environmental standards. Many of these organizations have also cited how the merger is likely to accelerate 4G wireless deployment, thus helping underserved communities such as rural areas and disadvantaged urban communities.[28]According to the NAACP, the merger will "advance increased access to affordable and sustainable wireless broadband services and in turn stimulate job creation and civic engagement throughout our country."[28]

As of August 2 the governors of 26 states have written letters supporting the merger.[29]On July 27 the attorneys general of Utah, Alabama, Arkansas, Georgia, Kentucky, Michigan, Mississippi, North Dakota, South Dakota, West Virginia, and Wyoming sent a joint letter of support to the FCC.[29]As of August 2011 state regulatory agencies in Arizona and Louisiana have approved the acquisition.

A diverse group of industry and public-interest organizations are opposed to AT&T's merger with T-Mobile. Consumer groups including Public Knowledge, Consumers Union, Free Press and the Media Access Project are publicly opposed to AT&T merger. These groups have influence with Democrats at the Federal Communications Commission and in Congress. These organizations fear that the merger will raise prices and stifle innovation by consolidating so much of the wireless industry in one company. Free Press and Public Knowledge have started letter-writing campaigns against the deal.[30]

Internet companies are generally skeptical of the merger because it leaves them with fewer counter-parties to negotiate with for getting their content and applications to customers. The AT&T merger might leave them dependent on just two, AT&T andVerizon. The Computer & Communication Industry Association (CCIA), which counts Google, Microsoft, Yahoo and eBay among its members, is opposed to the merger. "A deal like this, if not blocked on antitrust grounds, is of deep concern to all the innovative businesses that build everything from apps to handsets. It would be hypocritical for our nation to talk about unleashing innovation on one hand and then stand by as threats to innovation like this are proposed," said Ed Black, head of CCIA.[30]

On April 21, 2011, AT&T defended its proposed acquisition of T-Mobile USA before a U.S. Senate committee, saying the combined company will deliver high-speed wireless services to 97 percent of Americans and provide consumer benefits such as fewer dropped calls.[31]

If AT&T's acquisition of T-Mobile USA is rejected by federal regulators, AT&T would need to pay $6 billion, including $3 billion in cash, to T-Mobile USA's parent company Deutsche Telekom.[32]

On August 31, 2011, the Department of Justice officially filed a lawsuit in the United States District Court for the District of Columbia seeking to block the acquisition. [33][34]

On November 30, 2011, the FCC allowed AT&T to withdraw their merger, saving both carriers from divulging documentation about internal operations. The FCC cited job loss and higher consumer prices as reasons to deny the merger.[35]

On December 19, 2011, AT&T announced that it would permanently end its merger bid after a "thorough review of its options". The announcement included an assertion that the failure of the acquisition would increase costs to consumers and harm innovation in the wireless market. As per the original acquisition agreement, T-Mobile will receive $3 billion in cash as well as access to $1 billion worth of AT&T-held wireless spectrum.[36]

[edit]Political contributions and lobbying

According to the Center for Responsive Politics, AT&T is the second largest donor to United States political campaigns,[37]and the top American corporate donor,[38]having contributed more than US$47.7 million since 1990, 56% and 44% of which went toRepublicanand Democratic recipients, respectively.[39]Also, during the period of 1998 to 2010, the company expended US$130 million on lobbying in the United States.[38]A key political issue for AT&T has been the question of which businesses win the right to profit by providing broadband internet access in the United States.[40]

In 2005, AT&T was among 53 entities that contributed the maximum of $250,000 to the second inauguration of President George W. Bush.[41][42][43]

[edit]Bell Operating Companies

AT&T payphone signage.

Of the twenty-two Bell Operating Companies which AT&T Corp. owned prior to the 1984 agreement to divest, eleven (BellSouth Telecommunications combines two former BOCs) have become a part of the new AT&T Inc. with the completion of their acquisition of BellSouth Corporation on December 29, 2006:[44]

[edit]Former operating companies

The following companies have gone to defunct status under SBC/AT&T ownership:

[edit]Corporate structure

AT&T office in San Antonio, Texas with new logo and orange highlight from the former Cingular

AT&T Inc. has retained the holding companies it has acquired over the years resulting in the following corporate structure:

[edit]Corporate governance

Stephenson at the 2008 World Economic Forum

AT&T's current board of directors:[45]

[edit]Criticism and controversies[edit]Wireless service

AT&T has received criticisms for its wireless services. In December 2010, Consumer Reports named AT&T as the worst wireless provider in the country.[46]In 2011, AT&T has been rated the worst wireless provider for the second year in a row.[47]

[edit]Censorship

In August 2009, the band Pearl Jam performed in Chicago at Lollapalooza which was being web-broadcast by AT&T. The band, while playing the song "Daughter", started playing a version of Pink Floyd's "Another Brick in the Wall" but with altered lyrics critical of president George Bush. These lyrics included "George Bush, leave this world alone!" and, "George Bush, find yourself another home!". Listeners to AT&T's web broadcast heard only the first line because the rest was censored,[48]although AT&T spokesman Michael Coe said that the silencing was "a mistake."[49]

In September 2007, AT&T changed[50]their legal policy to state that "AT&T may immediately terminate or suspend all or a portion of your Service, any Member ID, electronic mail address, IP address, Universal Resource Locator or domain name used by you, without notice for conduct that AT&T believes"..."(c) tends to damage the name or reputation of AT&T, or its parents, affiliates and subsidiaries."[51]By October 10, 2007 AT&T had altered the terms and conditions for its Internet service to explicitly support freedom of expression by its subscribers, after an outcry claiming the company had given itself the right to censor its subscribers' transmissions.[52]

Section 5.1 of AT&T's new terms of service now reads "AT&T respects freedom of expression and believes it is a foundation of our free society to express differing points of view. AT&T will not terminate, disconnect or suspend service because of the views you or we express on public policy matters, political issues or political campaigns."[53][dubious- discuss]

On July 26, 2009, AT&T customers were unable to access certain sections of the image board 4chan, specifically /b/ (the "random" board) and /r9k/ (the "ROBOT 9000" board, a spin-off of the random board).[54]However, by the morning of Monday, July 27, the block had been lifted and access to the affected boards was restored. AT&T's official reason for the block was that a distributed denial of service attack had originated from the img.4chan.org server, and access was blocked to stop the attack.[55]Major news outlets have reported that the issue may be related to DDoSing of 4chan, and that the suspicions of 4chan users fell on AnonTalk.com (later AnonTalk.se) at that time for doing this.[56]

[edit]Privacy controversy

Diagram of how alleged wiretapping worked. From EFF court filings[57]

Further information: NSA call database, Mark Klein, NSA warrantless surveillance controversy, Hepting v. AT&T

In 2006, the Electronic Frontier Foundation lodged a class action lawsuit, Hepting v. AT&T, which alleged that AT&T had allowed agents of the National Security Agency (NSA) to monitor phone and Internet communications of AT&T customers without warrants. If true, this would violate the Foreign Intelligence Surveillance Act of 1978 and the First and Fourth Amendments of the U.S. Constitution. AT&T has yet to confirm or deny that monitoring by the NSA is occurring. In April 2006, a retired former AT&T technician, Mark Klein, lodged an affidavit supporting this allegation.[58][59]The Department of Justice has stated they will intervene in this lawsuit by means of State Secrets Privilege.[60]In July 2006, the United States District Court for the Northern District of California - in which the suit was filed - rejected a federal government motion to dismiss the case. The motion to dismiss, which invoked the State Secrets Privilege, had argued that any court review of the alleged partnership between the federal government and AT&T would harm national security. The case was immediately appealed to the Ninth Circuit. It was dismissed on June 3, 2009, citing retroactive legislation in the Foreign Intelligence Surveillance Act. [61] In May 2006, USA Todayreported that all international and domestic calling records had been handed over to the National Security Agency by AT&T, Verizon, SBC, and BellSouth for the purpose of creating a massive calling database.[62]The portions of the new AT&T that had been part of SBC Communications before November 18, 2005 were not mentioned.

On June 21, 2006, the San Francisco Chronicle reported that AT&T had rewritten rules on their privacy policy. The policy, which took effect June 23, 2006, says that "AT&T - not customers - owns customers' confidential info and can use it 'to protect its legitimate business interests, safeguard others, or respond to legal process.' "[63]

On August 22, 2007, National Intelligence Director Mike McConnell confirmed that AT&T was one of the telecommunications companies that assisted with the government's warrantless wire-tapping program on calls between foreign and domestic sources.[64]

On November 8, 2007, Mark Klein, a former AT&T technician, told Keith Olbermann of MSNBC that all Internet traffic passing over AT&T lines was copied into a locked room at the company's San Francisco office - to which only employees with National Security Agency clearance had access.[65]

AT&T keeps for five to seven years a record of who text messages whom and the date and time, but not the content of the messages.[66]

[edit]Intellectual property filtering

In January 2008, the company reported plans to begin filtering all Internet traffic which passes through its network for intellectual property violations.[67]Commentators in the media have speculated that if this plan is implemented, it would lead to a mass exodus of subscribers leaving AT&T,[68]although this is misleading as Internet traffic may go through the company's network anyway.[67]Internet freedom proponents used these developments as justification for government-mandated network neutrality.

[edit]Discrimination against local Public-access television channels

AT&T is accused by community media groups of discriminating against local Public, educational, and government access (PEG) cable TV channels:, by "imposing unfair restrictions that will severely restrict the audience".[69]

According to Barbara Popovic, Executive Director of the Chicago public-access service CAN-TV, the new AT&T U-verse system forces all Public-access television into a special menu system, denying normal functionality such as channel numbers, access to the standard program guide, and DVR recording.[69]The Ratepayer Advocates division of the California Public Utilities Commission reported: "Instead of putting the stations on individual channels, AT&T has bundled community stations into a generic channel that can only be navigated through a complex and lengthy process."[69]

Sue Buske (president of telecommunications consulting firm the Buske Group and a former head of the National Federation of Local Cable Programmers/Alliance for Community Media) argue that this is "an overall attack [...] on public access across the [United States], the place in the dial around cities and communities where people can make their own media in their own communities".[69]

[edit]Information security

In June 2010, a hacker group known as Goatse Security discovered a vulnerability within the AT&T that could allow anyone to uncover email addresses belonging to customers of AT&T 3G service for the Apple iPad.[70]These email addresses could be accessed without a protective password.[71]Using a script, Goatse Security collected thousands of email addresses from AT&T.[70]Goatse Security informed AT&T about the security flaw through a third party.[72]Goatse Security then disclosed around 114,000 of these emails to Gawker Media, which published an article about the security flaw and disclosure in Valleywag.[70][72]Praetorian Security Group criticized the web application that Goatse Security exploited as "poorly designed".[70]

What is the importance of the Morse code?

A: Today it has not much value except for die hard amateurs radio operator. At one time it was extensively used because the range of communication at low frequency transmission dot line it could circumvent the globe Nowadays with the satellite circling the globe it has become a curiosity. The generation of the code was done with breaking a switch to cause the transmitter to output a wave more popular was dedicated wires whereas the useful transmission

Write an essay of around 2000 words on 'Evolution of management accounting discipline and its relationship with other functions in organizations'.?

Early telecommunicationsA replica of one of Chappe's semaphore towers

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 was during the Spanish Armada, when a beacon chain relayed a signal from Plymouth to London signalling the arrival of Spanish ships.[1]

In 1792, Claude Chappe, a French engineer, built the first fixed visual telegraphy system (or semaphore line) between Lille and Paris.[2] 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 the electrical telegraph, the last commercial line was abandoned in 1880.[3]

[edit] Telegraph and telephoneThe first commercial electrical telegraph was constructed by Sir Charles Wheatstone and Sir William Fothergill Cooke and opened on 9 April 1839. Both Wheatstone and Cooke viewed their device as "an improvement to the [existing] electromagnetic telegraph" not as a new device.[4]

Samuel Morse independently developed a version of the electrical telegraph that he unsuccessfully demonstrated on 2 September 1837. His code was an important advance over Wheatstone's signaling method. The first transatlantic telegraph cable was successfully completed on 27 July 1866, allowing transatlantic telecommunication for the first time.[5]

The conventional telephone was invented independently by Alexander Bell and Elisha Gray in 1876.[6] Antonio Meucci invented the first device that allowed the electrical transmission of voice over a line in 1849. However Meucci's device was of little practical value because it relied upon the electrophonic effect and thus required users to place the receiver in their mouth to "hear" what was being said.[7] The first commercial telephone services were set-up in 1878 and 1879 on both sides of the Atlantic in the cities of New Haven and London.[8][9]

[edit] Radio and televisionIn 1832, James Lindsay gave a classroom demonstration of wireless telegraphy to his students. By 1854, he was able to demonstrate a transmission across the Firth of Tay from Dundee, Scotland to Woodhaven, a distance of two miles (3 km), using water as the transmission medium.[10] In December 1901, Guglielmo Marconi established wireless communication between St. John's, Newfoundland (Canada) and Poldhu, Cornwall (England), earning him the 1909 Nobel Prize in physics (which he shared with Karl Braun).[11] However small-scale radio communication had already been demonstrated in 1893 by Nikola Tesla in a presentation to the National Electric Light Association.[12]

On 25 March 1925, John Logie Baird was able to demonstrate the transmission of moving pictures at the London department store Selfridges. Baird's device relied upon the Nipkow disk and thus became known as the mechanical television. It formed the basis of experimental broadcasts done by the British Broadcasting Corporation beginning 30 September 1929.[13] However, for most of the twentieth century televisions depended upon the cathode ray tube invented by Karl 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.[14]

[edit] Computer networks and the InternetOn 11 September 1940, George Stibitz was able to transmit problems using teletype to his Complex Number Calculator in New York and receive the computed results back at Dartmouth College in New Hampshire.[15] This configuration of a centralized computer or mainframe with remote dumb terminals remained popular throughout the 1950s. However, it was not until the 1960s that researchers started to investigate packet switching - a technology that would allow chunks of data to be sent to different computers without first passing through a centralized mainframe. A four-node network emerged on 5 December 1969; this network would become ARPANET, which by 1981 would consist of 213 nodes.[16]

ARPANET's development centred around the Request for Comment process and on 7 April 1969, RFC 1 was published. This process is important because ARPANET would eventually merge with other networks to form the Internet and many of the protocols the Internet relies upon today were specified through the Request for Comment process. In September 1981, RFC 791 introduced the Internet Protocol v4 (IPv4) and RFC 793 introduced the Transmission Control Protocol (TCP) - thus creating the TCP/IP protocol that much of the Internet relies upon today.

However, not all important developments were made through the Request for Comment process. Two popular link protocols for local area networks (LANs) also appeared in the 1970s. A patent for the token ring protocol was filed by Olof Soderblom on 29 October 1974 and a paper on the Ethernet protocol was published by Robert Metcalfe and David Boggs in the July 1976 issue of Communications of the ACM.[17][18]

[edit] Key conceptsEtymology The word telecommunication was adapted from the French word télécommunication. It is a compound of the Greek prefix tele- (τηλε-), meaning 'far off', and the Latin communicare, meaning 'to share'.[19] The French word télécommunication was coined in 1904 by French engineer and novelist Édouard Estaunié.[20]

A number of key concepts reoccur throughout the literature on modern telecommunication systems. Some of these concepts are discussed below.

[edit] Basic elementsA basic telecommunication system consists of three elements:
  • a transmitter that takes information and converts it to a signal;
  • a transmission medium that carries the signal; and,
  • a receiver that receives the signal and converts it back into usable information.

For example, in a radio broadcast the broadcast tower is the transmitter, free space is the transmission medium and the radio is the receiver. Often telecommunication systems are two-way with a single device acting as both a transmitter and receiver or transceiver. For example, a mobile phone is a transceiver.[21]

Telecommunication over a telephone line is called point-to-point communication because it is between one transmitter and one receiver. Telecommunication through radio broadcasts is called broadcast communication because it is between one powerful transmitter and numerous receivers.[21]

[edit] Analogue or digitalSignals can be either analogue or digital. In an analogue signal, the signal is varied continuously with respect to the information. In a digital signal, the information is encoded as a set of discrete values (for example ones and zeros). During transmission the information contained in analogue signals will be degraded by noise. Conversely, unless the noise exceeds a certain threshold, the information contained in digital signals will remain intact. Noise resistance represents a key advantage of digital signals over analogue signals.[22] [edit] NetworksA network is a collection of transmitters, receivers and transceivers that communicate with each other. Digital networks consist of one or more routers that work together to transmit information to the correct user. An analogue network consists of one or more switches that establish a connection between two or more users. For both types of network, 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 noise.[23] [edit] ChannelsA channel is a division in a transmission medium so that it can be used to send multiple streams of information. For example, a radio station may broadcast at 96.1 MHz while another radio station may broadcast at 94.5 MHz. In this case, the medium has been divided by frequency and each channel has received a separate frequency to broadcast on. Alternatively, one could allocate each channel a recurring segment of time over which to broadcast-this is known as time-division multiplexing and is sometimes used in digital communication.[23] [edit] ModulationThe 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 is known as keying and several keying techniques exist (these include phase-shift keying, frequency-shift keying and amplitude-shift keying). Bluetooth, for example, uses phase-shift keying to exchange information between devices.[24][25]

Modulation can also be used to transmit the information of 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 superimposed on 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 and frequency modulation). An example of this process is a DJ's voice being superimposed on a 96 MHz carrier wave using frequency modulation (the voice would then be received on a radio as the channel "96 FM").[26]

[edit] Society and telecommunicationTelecommunication has a significant social, cultural and economic impact on modern society. In 2006, estimates placed the telecommunication industry's revenue at $1.2 trillion (USD) or just under 3% of the gross world product (official exchange rate).[27] [edit] Economic impact[edit] Microeconomics

On the microeconomic scale, companies have used telecommunication to help build global empires. This is self-evident in the case of online retailer Amazon.com but, according to academic Edward Lenert, even the conventional retailer Wal-Mart has benefited from better telecommunication infrastructure compared to its competitors.[28] In cities throughout the world, home owners use their telephones to organize many home services ranging from pizza deliveries to electricians. Even relatively poor communities have been noted to use telecommunication to their advantage. In Bangladesh's Narshingdi district, isolated villagers use cell phones to speak directly to wholesalers and arrange a better price for their goods. In Cote d'Ivoire, coffee growers share mobile phones to follow hourly variations in coffee prices and sell at the best price.[29]

[edit] Macroeconomics

On the macroeconomic scale, Lars-Hendrik Röller and Leonard Waverman suggested a causal link between good telecommunication infrastructure and economic growth.[30] Few dispute the existence of a correlation although some argue it is wrong to view the relationship as causal.[31]

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 one-third of countries have less than 1 mobile subscription for every 20 people and one-third of countries have less than 1 fixed line subscription for every 20 people. In terms of Internet access, roughly half of all countries have less than 1 in 20 people with Internet access. From this information, as well as educational data, the ITU was able to compile an index that measures the overall ability of citizens to access and use information and communication technologies.[32] Using this measure, Sweden, Denmark and Iceland received the highest ranking while the African countries Niger, Burkina Faso and Mali received the lowest.[33]

[edit] Social impactTelecommunication is playing an increasingly important role in social relationships. 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 a person's age, interests, sexuality and relationship status. In this way, these sites can play important role in everything from organising social engagements to courtship.[34]

Prior to social networking sites, technologies like 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 the United Kingdom had used the service to coordinate social arrangements and 42% to flirt.[35]

[edit] Other impactsIn cultural terms, telecommunication has increased the public's ability to access to 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 the music store.

Telecommunication has also transformed the way people receive their news. A survey by the non-profit Pew Internet and American Life Project found that when just over 3,000 people living in the United States were asked where they got their news "yesterday", more people said television or radio than newspapers. The results are summarised in the following table (the percentages add up to more than 100% because people were able to specify more than one source).[36]Local TVNational TVRadioLocal paperInternetNational paper59% 47% 44% 38% 23% 12%

Telecommunication has had an equally significant impact on advertising. TNS Media Intelligence reported that in 2007, 58% of advertising expenditure in the United States was spent on mediums that depend upon telecommunication.[37] The results are summarised in the following table.

InternetRadioCable TVSyndicated TVSpot TVNetwork TVNewspaperMagazineOutdoorTotalPercent7.6% 7.2% 12.1% 2.8% 11.3% 17.1% 18.9% 20.4% 2.7% 100%Dollars$11.31 billion $10.69 billion $18.02 billion $4.17 billion $16.82 billion $25.42 billion $28.22 billion $30.33 billion $4.02 billion $149 billion

[edit] Modern operation[edit] TelephoneOptical fiber provides cheaper bandwidth for long distance communication

In an analogue telephone network, the caller is connected to the person he wants to talk to 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 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. There is a separate electrical connection that works in reverse, allowing the users to converse.[38][39]

The fixed-line telephones in most residential homes are analogue - that is, the speaker's voice directly determines the signal's voltage. Although short-distance calls may be handled from end-to-end as analogue signals, increasingly telephone service providers are transparently converting the signals to digital for transmission before converting them back to analogue for reception. The advantage of this is that digitized voice data can travel side-by-side with data from the Internet and can be perfectly reproduced in long distance communication (as opposed to analogue signals that are inevitably impacted by noise).

Mobile phones have had a significant impact on telephone networks. Mobile phone subscriptions now outnumber fixed-line subscriptions in many markets. Sales of mobile phones in 2005 totalled 816.6 million with that figure being almost equally shared amongst the markets of Asia/Pacific (204 m), Western Europe (164 m), CEMEA (Central Europe, the Middle East and Africa) (153.5 m), North America (148 m) and Latin America (102 m).[40] In terms of new subscriptions over the five years from 1999, Africa has outpaced other markets with 58.2% growth.[41] Increasingly these phones are being serviced by systems where the voice content is transmitted digitally such as GSM or W-CDMA with many markets choosing to depreciate analogue systems such as AMPS.[42]

There have also been dramatic changes in telephone communication behind the scenes. Starting with the operation of TAT-8 in 1988, the 1990s saw the widespread adoption of systems based on optic fibres. The benefit of communicating with optic fibres is that they offer a drastic increase in data capacity. TAT-8 itself was able to carry 10 times as many telephone calls as the last copper cable laid at that time and today's optic fibre cables are able to carry 25 times as many telephone calls as TAT-8.[43] This increase in data capacity is due to several factors: First, optic fibres are physically much smaller than competing technologies. Second, they do not suffer from crosstalk which means several hundred of them can be easily bundled together in a single cable.[44] Lastly, improvements in multiplexing have led to an exponential growth in the data capacity of a single fibre.[45][46]

Assisting communication across many modern optic fibre networks is a protocol known as Asynchronous Transfer Mode (ATM). The ATM protocol allows for the side-by-side data transmission mentioned in the second paragraph. It is suitable for public telephone networks because it establishes a pathway for data through the network and associates a traffic contract with that pathway. The traffic contract is essentially an agreement between the client and the network about how the network is to handle the data; if the network cannot meet the conditions of the traffic contract it does not accept the connection. This is important because telephone calls can negotiate a contract so as to guarantee themselves a constant bit rate, something that will ensure a caller's voice is not delayed in parts or cut-off completely.[47] There are competitors to ATM, such as Multiprotocol Label Switching (MPLS), that perform a similar task and are expected to supplant ATM in the future.[48]

[edit] Radio and televisionDigital television standards and their adoption worldwide.

In a broadcast system, a central high-powered broadcast tower transmits a high-frequency electromagnetic wave to numerous low-powered receivers. The high-frequency wave sent by the tower is modulated with a signal containing visual or audio information. The antenna of the receiver is then tuned so as to pick up the high-frequency wave and a demodulator is used to retrieve the signal containing the visual or audio information. The broadcast signal can be either analogue (signal is varied continuously with respect to the information) or digital (information is encoded as a set of discrete values).[49][50]

The broadcast media industry is at a critical turning point in its development, with many countries moving from analogue to digital broadcasts. This move is made possible by the production of cheaper, faster and more capable integrated circuits. The chief advantage of digital broadcasts is that they prevent a number of complaints with traditional analogue broadcasts. For television, this includes the elimination of problems such as snowy pictures, ghosting and other distortion. These occur because of the nature of analogue transmission, which means that perturbations due to noise will be evident in the final output. Digital transmission overcomes this problem because digital signals are reduced to discrete values upon reception and hence small perturbations do not affect the final output. In a simplified example, if a binary message 1011 was transmitted with signal amplitudes [1.0 0.0 1.0 1.0] and received with signal amplitudes [0.9 0.2 1.1 0.9] it would still decode to the binary message 1011 - a perfect reproduction of what was sent. From this example, a problem with digital transmissions can also be seen in that if the noise is great enough it can significantly alter the decoded message. Using forward error correction a receiver can correct a handful of bit errors in the resulting message but too much noise will lead to incomprehensible output and hence a breakdown of the transmission.[51][52]

In digital television broadcasting, there are three competing standards that are likely to be adopted worldwide. These are the ATSC, DVB and ISDB standards; the adoption of these standards thus far is presented in the captioned map. All three standards use MPEG-2 for video compression. ATSC uses Dolby Digital AC-3 for audio compression, ISDB uses Advanced Audio Coding (MPEG-2 Part 7) and DVB has no standard for audio compression but typically uses MPEG-1 Part 3 Layer 2.[53][54] The choice of modulation also varies between the schemes. In digital audio broadcasting, standards are much more unified with practically all countries choosing to adopt the Digital Audio Broadcasting standard (also known as the Eureka 147 standard). The exception being the United States which has chosen to adopt HD Radio. HD Radio, unlike Eureka 147, is based upon a transmission method known as in-band on-channel transmission that allows digital information to "piggyback" on normal AM or FM analogue transmissions.[55]

However, despite the pending switch to digital, analogue television remains transmitted in most countries. An exception is the United States that ended analogue television transmission on the 12th of June 2009[56] after twice delaying the switch over deadline. For analogue television, there are three standards in use (see a map on adoption here). These are known as PAL, NTSC and SECAM. For analogue radio, the switch to digital is made more difficult by the fact that analogue receivers are a fraction of the cost of digital receivers.[57][58] The choice of modulation for analogue radio is typically between amplitude modulation (AM) or frequency modulation (FM). To achieve stereo playback, an amplitude modulated subcarrier is used for stereo FM.

[edit] The InternetThe OSI reference model

The Internet is a worldwide network of computers and computer networks that can communicate with each other using the Internet Protocol.[59] Any computer on the Internet has a unique IP address that can be used by other computers to route information to it. Hence, any computer on the Internet can send a message to any other computer using its IP address. These messages carry with them the originating computer's IP address allowing for two-way communication. In this way, the Internet can be seen as an exchange of messages between computers.[60]

As of 2008[update], an estimated 21.9% of the world population has access to the Internet with the highest access rates (measured as a percentage of the population) in North America (73.6%), Oceania/Australia (59.5%) and Europe (48.1%).[61] In terms of broadband access, Iceland (26.7%), South Korea (25.4%) and the Netherlands (25.3%) led the world.[62]

The Internet works in part because of protocols that govern how the computers and routers communicate with each other. The nature of computer network communication lends itself to a layered approach where individual protocols in the protocol stack run more-or-less independently of other protocols. This allows lower-level protocols to be customized for the network situation while not changing the way higher-level protocols operate. A practical example of why this is important is because it allows an Internet browser to run the same code regardless of whether the computer it is running on is connected to the Internet through an Ethernet or Wi-Fi connection. Protocols are often talked about in terms of their place in the OSI reference model (pictured on the right), which emerged in 1983 as the first step in an unsuccessful attempt to build a universally adopted networking protocol suite.[63]

For the Internet, the physical medium and data link protocol can vary several times as packets traverse the globe. This is because the Internet places no constraints on what physical medium or data link protocol is used. This leads to the adoption of media and protocols that best suit the local network situation. In practice, most intercontinental communication will use the Asynchronous Transfer Mode (ATM) protocol (or a modern equivalent) on top of optic fibre. This is because for most intercontinental communication the Internet shares the same infrastructure as the public switched telephone network.

At the network layer, things become standardized with the Internet Protocol (IP) being adopted for logical addressing. For the world wide web, these "IP addresses" are derived from the human readable form using the Domain Name System (e.g. 72.14.207.99 is derived from www.Google.com). At the moment, the most widely used version of the Internet Protocol is version four but a move to version six is imminent.[64]

At the transport layer, most communication adopts either the Transmission Control Protocol (TCP) or the User Datagram Protocol (UDP). TCP is used when it is essential every message sent is received by the other computer where as UDP is used when it is merely desirable. With TCP, packets are retransmitted if they are lost and placed in order before they are presented to higher layers. With UDP, packets are not ordered or retransmitted if lost. Both TCP and UDP packets carry port numbers with them to specify what application or process the packet should be handled by.[65] Because certain application-level protocols use certain ports, network administrators can restrict Internet access by blocking the traffic destined for a particular port.

Above the transport layer, there are certain protocols that are sometimes used and loosely fit in the session and presentation layers, most notably the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols. These protocols ensure that the data transferred between two parties remains completely confidential and one or the other is in use when a padlock appears in the address bar of your web browser.[66] Finally, at the application layer, are many of the protocols Internet users would be familiar with such as HTTP (web browsing), POP3 (e-mail), FTP (file transfer), IRC (Internet chat), BitTorrent (file sharing) and OSCAR (instant messaging).

[edit] Local area networksDespite the growth of the Internet, the characteristics of local area networks (computer networks that run at most a few kilometres) remain distinct. This is because networks on this scale do not require all the features associated with larger networks and are often more cost-effective and efficient without them.

In the mid-1980s, several protocol suites emerged to fill the gap between the data link and applications layer of the OSI reference model. These were Appletalk, IPX and NetBIOS with the dominant protocol suite during the early 1990s being IPX due to its popularity with MS-DOS users. TCP/IP existed at this point but was typically only used by large government and research facilities.[67] As the Internet grew in popularity and a larger percentage of traffic became Internet-related, local area networks gradually moved towards TCP/IP and today networks mostly dedicated to TCP/IP traffic are common. The move to TCP/IP was helped by technologies such as DHCP that allowed TCP/IP clients to discover their own network address - a functionality that came standard with the AppleTalk/IPX/NetBIOS protocol suites.[68]

It is at the data link layer though that most modern local area networks diverge from the Internet. Whereas Asynchronous Transfer Mode (ATM) or Multiprotocol Label Switching (MPLS) are typical data link protocols for larger networks, Ethernet and Token Ring are typical data link protocols for local area networks. These protocols differ from the former protocols in that they are simpler (e.g. they omit features such as Quality of Service guarantees) and offer collision prevention. Both of these differences allow for more economic set-ups.[69]

Despite the modest popularity of Token Ring in the 80's and 90's, virtually all local area networks now use wired or wireless Ethernet. At the physical layer, most wired Ethernet implementations use copper twisted-pair cables (including the common 10BASE-T networks). However, some early implementations used coaxial cables and some recent implementations (especially high-speed ones) use optic fibres.[70] Where optic fibre is used, the distinction must be made between multi-mode fibre and single-mode fibre. Multi-mode fibre can be thought of as thicker optical fibre that is cheaper to manufacture but that suffers from less usable bandwidth and greater attenuation (i.e. poor long-distance performance).[71]

[edit] Telecommunication by region[show] v • d • e

Telecommunications in EuropeSovereign

states

Albania · Andorra · Armenia1 · Austria · Azerbaijan2 · Belarus · Belgium ·Bosnia and Herzegovina · Bulgaria · Croatia ·Cyprus1 · Czech Republic · Denmark · Estonia · Finland · France · Georgia2 · Germany · Greece · Hungary · Iceland · Ireland · Italy · Kazakhstan3 · Latvia ·Liechtenstein · Lithuania · Luxembourg ·Republic of Macedonia · Malta · Moldova ·Monaco · Montenegro · Netherlands · Norway · Poland · Portugal · Romania · Russia3 · San Marino · Serbia · Slovakia ·Slovenia · Spain · Sweden · Switzerland · Turkey3 · Ukraine · United Kingdom (England • Northern Ireland • Scotland • Wales)

Other entities

European Union · Sovereign Military Order of Malta

Dependencies,

autonomies,

other territories

Abkhazia 2 · Adjara1 · Adygea ·Akrotiri and Dhekelia · Åland · Azores ·Bashkortostan · Catalonia · Chechnya ·Chuvashia · Crimea · Dagestan · Faroe Islands · Gagauzia · Gibraltar · Guernsey ·Ingushetia · Jan Mayen · Jersey ·Kabardino-Balkaria · Kalmykia · Karachay-Cherkessia · Republic of Karelia · Komi Republic ·Kosovo · Madeira · Isle of Man · Mari El · Mordovia · Nagorno-Karabakh1 ·Nakhchivan1 · North Ossetia-Alania · Northern Cyprus1 · South Ossetia 2 · Svalbard · Tatarstan · Transnistria · Udmurtia · Vojvodina

Italics indicates an unrecognised or partially recognised country. 1 Entirely in Asia, but historically considered European. 2 Partially or entirely in Asia, depending on the border definitions. 3 Transcontinental country.[show] v • d • e

Telecommunications in North AmericaSovereign states

Antigua and Barbuda · Bahamas · Barbados ·Belize · Canada · Costa Rica · Cuba ·Dominica · Dominican Republic · El Salvador ·Grenada · Guatemala · Haiti · Honduras · Jamaica · Mexico · Nicaragua ·Panama1 · Saint Kitts and Nevis · Saint Lucia · Saint Vincent and the Grenadines · Trinidad and Tobago1 · United States

Dependencies and

other territories

Anguilla · Aruba1 · Bermuda · British Virgin Islands · Cayman Islands · Greenland ·Guadeloupe · Martinique · Montserrat · Navassa Island · Netherlands Antilles1 · Puerto Rico ·Saint Barthélemy · Saint Martin · Saint Pierre and Miquelon · Turks and Caicos Islands · United States Virgin Islands

1 Territories also in or commonly considered to be part of South America.[show] v • d • e

Telecommunications in South AmericaSovereign states

Argentina · Bolivia · Brazil · Chile · Colombia · Ecuador · Guyana · Panama1 · Paraguay · Peru · Suriname · Trinidad and Tobago1 · Uruguay · Venezuela

Dependencies

Aruba1 / Netherlands Antilles1 (Netherlands) · Falkland Islands / South Georgia and the South Sandwich Islands (UK) 2 / French Guiana (France)

1 Territories also in or commonly considered to be part of North America and/or Central America. 2 Territories also in or commonly considered to be part of Antarctica.[show] v • d • e

Telecommunications in OceaniaSovereign states

Australia · East Timor1 · Fiji · Indonesia1 · Kiribati · Papua New Guinea · Marshall Islands · Federated States of Micronesia · Nauru · New Zealand · Palau · Samoa · Solomon Islands · Tonga · Tuvalu · Vanuatu

Dependencies and

other territories

American Samoa · Christmas Island · Cocos (Keeling) Islands · Cook Islands · French Polynesia · Guam · Hawaii · New Caledonia · Niue · Norfolk Island · Northern Mariana Islands ·Pitcairn Islands · Tokelau · Wallis and Futuna

1 Transcontinental country.[show] v • d • e

Telecommunications in AfricaSovereign states

Algeria · Angola · Benin · Botswana · Burkina Faso · Burundi · Cameroon ·Cape Verde · Central African Republic · Chad ·Comoros · Democratic Republic of the Congo · Republic of the Congo · Côte d'Ivoire (Ivory Coast) · Djibouti · Egypt1 · Equatorial Guinea · Eritrea · Ethiopia · Gabon · The Gambia · Ghana · Guinea · Guinea-Bissau · Kenya ·Lesotho · Liberia · Libya · Madagascar · Malawi · Mali · Mauritania ·Mauritius · Morocco · Mozambique · Namibia · Niger · Nigeria · Rwanda · São Tomé and Príncipe · Senegal · Seychelles · Sierra Leone · Somalia · South Africa · Sudan · Swaziland · Tanzania · Togo · Tunisia · Uganda · Zambia · Zimbabwe

Dependencies,

autonomies,

other territories

Canary Islands / Ceuta / Melilla (Spain) · Madeira (Portugal) · Mayotte / Réunion (France) ·Puntland · St. Helena (UK) · Socotra (Yemen) · Somaliland · Southern Sudan ·Western Sahara · Zanzibar (Tanzania)

Italics indicate an unrecognised or partially recognised country. 1 Transcontinental country.[show] v • d • e

Telecommunications in AsiaSovereign

states

Afghanistan · Armenia1 · Azerbaijan1 ·Bahrain · Bangladesh · Bhutan · Brunei · Burma2 · Cambodia · People's Republic of China · Cyprus1 · East Timor3 · Egypt4 · Georgia4 · India · Indonesia · Iran · Iraq · Israel · Japan · Jordan · Kazakhstan4 · North Korea · South Korea · Kuwait · Kyrgyzstan · Laos · Lebanon · Malaysia · Maldives · Mongolia ·Nepal · Oman · Pakistan · Philippines ·Qatar · Russia4 · Saudi Arabia · Singapore · Sri Lanka · Syria · Tajikistan ·Republic of China5 · Thailand · Turkey4 ·Turkmenistan · United Arab Emirates · Uzbekistan · Vietnam · Yemen

Dependencies,

autonomies,

other territories

Aceh · Adjara1 · Abkhazia1 ·Akrotiri and Dhekelia · Altai · British Indian Ocean Territory · Buryatia · Christmas Island ·Cocos (Keeling) Islands · Guangxi · Hong Kong · Inner Mongolia · Iraqi Kurdistan · Jakarta · Khakassia · Macau · Nagorno-Karabakh· Nakhchivan · Ningxia · Northern Cyprus · Palestine (Gaza Strip · West Bank) · Papua · Sakha · South Ossetia1 · Tibet · Tuva · West Papua · Xinjiang · Yogyakarta

Italics indicates an unrecognised or partially recognised country. 1 Sometimes included in Europe, depending on the border definitions. 2 Officially known as Myanmar. 3 Sometimes included in Oceania, and also known as Timor-Leste. 4 Transcontinental country. 5 Commonly known as Taiwan.[show] v • d • e

Telecommunications in the Caribbean

Anguilla · Antigua and Barbuda · Aruba ·Bahamas · Barbados · British Virgin Islands ·Cayman Islands · Cuba · Dominica · Dominican Republic · Grenada · Guadeloupe · Haiti · Jamaica · Martinique · Montserrat ·Netherlands Antilles · Puerto Rico · St. Barthélemy · St. Kitts and Nevis · St. Lucia · St. Martin · St. Vincent and the Grenadines · Trinidad and Tobago · Turks and Caicos Islands · U.S. Virgin Islands

Belize • Bermuda · Colombia · Costa Rica • French Guiana • Guatemala • Guyana • Honduras • Mexico • Nicaragua • Panama • Suriname · Venezuela ·

[edit] See alsoTelecommunication portal
  • Outline of telecommunication
[edit] References
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  28. ^ Lenert, Edward (10.1111/j.1460-2466.1998.tb02767.x). "A Communication Theory Perspective on Telecommunications Policy". Journal of Communication 48 (4): 3-23. doi:10.1111/j.1460-2466.1998.tb02767.x.
  29. ^ Mireille Samaan (April 2003) (PDF). The Effect of Income Inequality on Mobile Phone Penetration. Boston University Honors thesis. http://dissertations.bc.edu/cgi/viewcontent.cgi?article=1016&context=ashonors. Retrieved on 2007-06-08.
  30. ^ Röller, Lars-Hendrik; Leonard Waverman (2001). "Telecommunications Infrastructure and Economic Development: A Simultaneous Approach". American Economic Review 91(4): 909-923. ISSN 0002-8282.
  31. ^ Riaz, Ali (10.1177/016344397019004004). "The role of telecommunications in economic growth: proposal for an alternative framework of analysis". Media, Culture & Society19 (4): 557-583. doi:10.1177/016344397019004004.
  32. ^ "Digital Access Index (DAI)". itu.int. http://www.itu.int/ITU-D/ict/dai/. Retrieved on 2008-03-06.
  33. ^ World Telecommunication Development Report 2003, International Telecommunication Union, 2003.
  34. ^ "How do you know your love is real? Check Facebook". CNN. 2008-04-04. http://www.cnn.com/2008/LIVING/personal/04/04/facebook.love/index.HTML.
  35. ^ I Just Text To Say I Love You, Ipsos MORI, September 2005.
  36. ^ "Online News: For many home broadband users, the internet is a primary news source". Pew Internet Project. 2006-03-22. http://www.pewinternet.org/pdfs/PIP_News.and.Broadband.pdf.
  37. ^ "100 Leading National Advertisers" (PDF). Advertising Age. 2008-06-23. http://adage.com/images/random/datacenter/2008/spendtrends08.pdf. Retrieved on 2009-06-21.
  38. ^ How Telephone Works, HowStuffWorks.com, 2006.
  39. ^ Telephone technology page, ePanorama, 2006.
  40. ^ Gartner Says Top Six Vendors Drive Worldwide Mobile Phone Sales to 21% Growth in 2005, Gartner Group, 28 February 2006.
  41. ^ Africa Calling, Victor and Irene Mbarika, IEEE Spectrum, May 2006.
  42. ^ Ten Years of GSM in Australia, Australia Telecommunications Association, 2003.
  43. ^ Milestones in AT&T History, AT&T Knowledge Ventures, 2006.
  44. ^ Optical fibre waveguide, Saleem Bhatti, 1995.
  45. ^ Fundamentals of DWDM Technology, CISCO Systems, 2006.
  46. ^ Report: DWDM No Match for Sonet, Mary Jander, Light Reading, 2006.
  47. ^ Stallings, William (2004). Data and Computer Communications (7th edition (intl) ed.). Pearson Prentice Hall. pp. pp 337-366. Special:Booksources.
  48. ^ MPLS is the future, but ATM hangs on, John Dix, Network World, 2002
  49. ^ Haykin, Simon (2001). Communication Systems(4th ed.). John Wiley & Sons. pp. pp 1-3. Special:Booksources.
  50. ^ How Radio Works, HowStuffWorks.com, 2006.
  51. ^ Digital Television in Australia, Digital Television News Australia, 2001.
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  53. ^ HDV Technology Handbook, Sony, 2004.
  54. ^ Audio, Digital Video Broadcasting Project, 2003.
  55. ^ Status of DAB (USA), World DAB Forum, March 2005.
  56. ^ Brian Stelter (June 13, 2009). "Changeover to Digital TV Off to a Smooth Start". New York Times. http://www.nytimes.com/2009/06/14/business/media/14digital.HTML?_r=2&hp.
  57. ^ GE 72664 Portable AM/FM Radio, Amazon.com, June 2006.
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  59. ^ Robert E. Kahn and Vinton G. Cerf, What Is The Internet (And What Makes It Work), December 1999. (specifically see footnote xv)
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  62. ^ OECD Broadband Statistics, Organisation for Economic Co-operation and Development, December 2005.
  63. ^ History of the OSI Reference Model, The TCP/IP Guide v3.0, Charles M. Kozierok, 2005.
  64. ^ Introduction to IPv6, Microsoft Corporation, February 2006.
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  66. ^ T. Dierks and C. Allen, The TLS Protocol Version 1.0, RFC 2246, 1999.
  67. ^ Martin, Michael (2000). Understanding the Network (The Networker's Guide to AppleTalk, IPX, and NetBIOS), SAMS Publishing, Special:Booksources.
  68. ^ Ralph Droms, Resources for DHCP, November 2003.
  69. ^ Stallings, pp 500-526.
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  71. ^ Fiber Optic Cable Tutorial, Arc Electronics. . Retrieved June, 2007.
[edit] Further reading
  • OECD, Universal Service and Rate Restructuring in Telecommunications, Organisation for Economic Co-operation and Development (OECD) Publishing, 1991. Special:Booksources
[edit] External linksFind more about Telecommunication on Wikipedia's sister projects: Definitions from Wiktionary

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Images and media from Commons

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Learning resources from Wikiversity

  • ATIS Telecom Glossary
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  • Federal Communications Commission
  • IEEE Communications Society
  • International Telecommunication Union
  • Ericsson's Understanding Telecommunications at archive.org (Ericsson removed the book from their site in Sep 2005)

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  • This page was last modified on 4 July 2009 at 08:35.
  • Text is available under the Creative Commons Attribution/Share-Alike License; additional terms

How does transportation and communication affect settlement of people?

Transportation and communication means affect how far apart people can live. In communities with good transportation and communication networks, people can settle further apart.

Define the bandwidth of a frequency modulated signal?

I believe the bandwidth of ANY signal is defined as the range of frequencies

that encompasses 99% of the signal's power.

For an AM signal at anything less than 100% modulation, it's 2 x the highest

modulating frequency.

FM signals aren't that simple to characterize. "Cramer's Rule" says that the

bandwidth is 2 x (peak deviation + highest modulating frequency), but as

the 'modulation index' increases, that rule becomes a poorer approximation.

How and what does the telephone do?

Telephone cable wire is used as the medium for internet connection. With the incorporation of the internet and the telephone technologies, we can now conveniently and cost effectively exchange audio and video information.

Can you have dsl without a land line?

In short, No!

You can purchase a modem that works off the GSM network (mobile phone network). These modems are relatively inexpensive about £30 in the UK. All you need to do, is charge it up, add the SIM card and pair (link up) whatever device you want to use to access the internet. These devices create a wireless access point (wifi), so you do not require a traditional fixed landline. Once you pair up the device you want to use, then you now have access to the internet.

The other way to have access to the internet, is by using a mobile phone that has internet tethering abilities. It's more or less the same process as above, except you don't use a separate GSM modem, the mobile phone becomes a GSM modem instead (this option saves the purchase of buying extra kit).

Another option is to take a wifi enabled device and find a free wifi local hotspot. You can visit a local library, they normally provide access to the Internet and in the UK provide a computer as well, although access is not always free using this option. There is also satellite internet, which can be expensive.

Please see related links and related question for further information.

What are some similarities between old telephones and new telephones?

some similarity and difference

-both can make a phone call

-run on a power source

-has numbers

-have some mobile lines

-phones then were much bigger

-phones now are more advanced

-phones now are touch screen

-phones then weighed alot

What are top ten core companies for training in electronics and telecommunication engineering?

There are following companies available in and around delhi for internship:-


-IDEA

-VODAFONE

-AIRTEL

-TATA COMMUNICATIONS

-UNINOR

-E-INFOCHIPS

-ISRO(IF YOU ARE TOPPER,THEN ONLY THEY WILL ALLOW)

-RELIANCE

-INTEL

you can choose any of the above based on your interest.


How to get internship:-


-Firstly, you need to obtain "No objection Certificate" from your college.

-Now visit the company, in which you are interested , submit your NOC and your latest resume there.

-Companies every year collect candidate's resume, and based on that they will short list some students based on their needs and allow them for internship.

-If you get shortlisted then they will call you and after that you can pursue training there.

-every year companies follow this procedure.


Hope, I have cleared your doubt.


for any other query , please post it here.

best of luck

regards.