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In telecommunications, a long-distance call or trunk call is a telephone call made outside a defined local area, usually to another city. These calls are typically characterized by their higher per-minute cost ("national rate" or "overseas rate" instead of local rate), by terminating at a destination served by a different local telephone exchange or by being carried over intercity trunks or interexchange carriers instead of a direct line between two adjacent exchanges. A long-distance call is not necessarily synonymous with a call to another telephone area code. Before direct distance dial (first introduced in a handful of markets in 1951), all long-distance calls were operator assisted by a special long-distance operator even in exchanges where calls within the local exchange were direct dial. Completion of intercity calls was time-consuming and costly as each call was handled by multiple operators in multiple cities. Record keeping was also more complex, as the duration of every toll call had to be manually recorded for billing purposes. In some countries (such as Canada and the US) long-distance rates were historically kept artificially high to subsidise unprofitable flat-rate local residential services. Intense competition between long-distance phone companies narrowed these gaps significantly in most developed nations in the late 20th century, although international calls to some countries continue to carry artificially high tolls as governments in those nations use them as a lucrative source of tax revenue. == History == In 1892, AT&T built an interconnected long-distance telephone network, which reached from New York to Chicago, the technological limit for non-amplified wiring. Users often did not use their own phone for such connections, but made an appointment to use a special long-distance telephone booth or "silence cabinet" equipped with 4-wire telephones and other advanced technology. The invention of loading coils extended the range to Denver in 1911, again reaching a technological limit. A major research venture and contest led to the development of the audion—originally invented by Lee De Forest and greatly improved by others in the years between 1907 and 1914—which provided the means for telephone signals to reach from coast to coast. Such transcontinental calling was made possible in 1914 but was not showcased until early 1915, as a promotion for the upcoming Panama-Pacific Exposition in San Francisco in the spring of the same year.〔(Crystal Fire - Michael Riordan and Lillian Hoddeson - Google Books )〕 On January 25, 1915, Alexander Graham Bell ceremonially sent the first transcontinental telephone call from 15 Dey Street in New York City, which was received by his former assistant Thomas A. Watson at 333 Grant Avenue in San Francisco. This process, nevertheless, involved five intermediary telephone operators and took 23 minutes to connect by manually ''patching in'' the route of the call. On November 11, 1951, the first direct dial long-distance telephone call in North America was placed from Mayor M. Leslie Denning of Englewood, New Jersey to Mayor Frank Osborne of Alameda, California via AT&T's Bell System.〔(The mosquito crusades: a history of ... – Gordon M. Patterson – Google Books )〕 The ten digit call (seven digits plus a three-digit area code) was connected automatically within 18 seconds.〔(1951: First Direct-Dial Transcontinental Telephone Call ), AT&T Inc. Accessed June 8, 2007. Quote: "Nov. 10, 1951: Mayor M. Leslie Downing of Englewood, N.J., picked up a telephone and dialed 10 digits. Eighteen seconds later, he reached Mayor Frank Osborne in Alameda, Calif. The mayors made history as they chatted in the first customer-dialed long-distance call, one that introduced area codes."〕 The first subscriber trunk dialling in the United Kingdom was deployed December 5, 1958 with Elizabeth II placing a call from Bristol to Edinburgh.〔(【引用サイトリンク】title=Events in Telecommunications History: 1958, 'BT's history', btplc.com/ )〕 International calling After WWII, priority was given by AT&T in the USA and the various PTT entities in Europe to automating switching on the toll networks in their respective countries (initially for Operator Toll Dialing). Thus, when TAT-1 was opened for service, it was connected to international gateway offices at White Plains, NY and London that were already automated for ''domestic'' calls. These were designed to be able to automatically switch outward and inward international circuits as soon as common signalling standards (and political considerations) could be negotiated. However, at the outset, to set up an international call, multiple operators were required: one to originate the call and one at each national gateway to complete a call via either ringdown to a local operator or operator toll dialing. International Direct Dialling from London to Paris was first offered in March 1963, with Amsterdam following by the end of 1963. Simultaneously, operator-dialed transatlantic calling began March 30, 1963 with the originating international operator in Western Europe or the USA able to complete calls to the terminal station without further operator assistance via the gateway exchanges at White Plains, NY and London.〔(【引用サイトリンク】title= 100 Years of Telephone Switching: Part 1 )〕 Operator-dialed transpacific calling to Hawaii, Japan, and Australia began with the completion of the COMPAC cable, also in 1963.〔 By mid-1968, transatlantic cable capacity had increased to the point where scheduling calls between Western Europe, the UK, and USA was no longer necessary and calls were completed on demand. Transatlantic International Direct Dialing between New York (212, 718 and 914 area codes) and London (01 STD code) was introduced in 1970,〔(【引用サイトリンク】title=Events in Telecommunications History: 1970, 'BT's history', btplc.com/ )〕 with service extended to the whole of the USA and the 6 largest UK cities in 1971.〔(【引用サイトリンク】title=Events in Telecommunications History: 1971, 'BT's history', btplc.com/ )〕 Collect/Reverse Charge calling Various schemes were devised to allow large organisations to automatically accept collect calls, where the recipient pays long-distance charges for any call from a predefined area. A Zenith number in the late 1950s required an operator manually determine the destination number from a printed list; the 1967 Wide Area Telephone Service introduced the first automated toll-free telephone numbers, terminated on special fixed-rate trunks. By the 1980s, computerisation of the system allowed British Telecom "Linkline" 0800 freephone numbers and AT&T +1-800- toll-free numbers to be controlled by a database and terminated virtually anywhere with each inbound call itemised and billed individually. This smart network was further refined to provide toll-free number portability in the 1990s. Technical Issues Until the early 1980s a called party could instantly recognize an incoming long-distance call by its hiss or low level, due to the inherent signal loss and introduction of noise. The deployment of digital technologies such as pulse-code modulation and T-carrier circuits in the 1970s and 1980s let long-distance calls match the high voice quality of local calls. Improvements in switching technology, the deployment of high-capacity optical fibre and an increase in competition substantially lowered long-distance rates at the end of the 20th century. Using the Internet, the distinction between local and long-distance communication is fading to the point where an Internet call from the United States to Beijing carries a lower wholesale cost than a domestic landline call to a rural independent in small-town Iowa. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Long-distance calling」の詳細全文を読む スポンサード リンク
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