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A party line, or alternatively party wire,〔http://www.merriam-webster.com/dictionary/party%20line〕〔http://www.best-norman-rockwell-art.com/norman-rockwell-leslies-cover-1919-03-22-the-party-wire.html〕 multiparty line, or (chiefly UK) shared service (line),〔http://www.telephonesuk.co.uk/shared_service.htm〕 is a local loop telephone circuit that is shared by multiple telephone service subscribers. Party line systems were widely used to provide telephone service, starting with the first commercial switchboards in 1878. A majority of Bell System subscribers in the mid-20th century in the United States and Canada were serviced by party lines, which carried a billing discount over individual service; during wartime shortages, these were often the only available lines. British users similarly benefited from the party line discount. Farmers in rural Australia used party lines, where a single line spanned miles from the nearest town to one property and on to the next.〔(Subscriber Trunk Dialling Call Zones ), NSW State Parliament speech, May 3, 2000〕 ==History== Telephone companies offered party lines since the late 1800s, although subscribers in all but the most rural areas may have had the option to upgrade to private line service at an additional monthly charge. The service was common in sparsely-populated areas where remote properties are spread across large distances, such as Australia (where these were operated by the Government Post Master General department). In rural areas in the early 20th century, additional subscribers and telephones, often numbered in several dozen, were frequently connected to the single loop available. Party lines provided no privacy in communication. They were frequently used as a source of entertainment and gossip, as well as a means of quickly alerting entire neighbourhoods of emergencies such as fires,〔Such a system in described in 〕 becoming a cultural fixture of rural areas for many decades. The rapid growth of telephone service demand, especially after WW-II, resulted in a large fraction of party line installations in the middle of the 20th century in the United States. This often led to traffic congestion in the telephone network, as the line to a destination telephone was often busy. Nearly three-quarters of Pennsylvania residential service in 1943 was party line, with users encouraged to limit calls to five minutes. Shortages persisted for years after each war; private lines in Montreal remained in short supply at the end of 1919 and similar shortages were reported by telephone companies in Florida as late as 1948, Some rural users had to run their own wires to reach the utility's lines. Objections about one party monopolizing a multi-party line were a staple of complaints to telephone companies and letters to advice columnists for years and eavesdropping on calls remained an ongoing concern. In December 1942, University of Tennessee's strategy in an American football game versus University of Mississippi was revealed to the opposing coach as a telephone on the Ole Miss team's bench had been inadvertently wired to the same party line. In May 1952, an alleged bookmaking operation in St. Petersburg, Florida was shut down after one month of operation in a rented storefront using a party line telephone. In June 1968, the conviction of three Winter Park, Florida men on bookmaking charges was overturned as police had used a party line telephone in a rented house on the same line as the suspects to unlawfully intercept their communications. In 1956, Southern Bell officials refused a request from a public utilities commissioner in Jackson, Mississippi to segregate party telephone lines on racial boundaries. While primitive lockout devices to prevent two subscribers from picking up the same line at the same time were proposed relatively early, multiple simultaneous calls did not become viable until the initial tests of transistorised pair gain devices in 1955. Any handset off-hook therefore tied up the line for everyone. Many jurisdictions require a person engaged in a call on a party line to end the call immediately if another party needs the line for an emergency. Such laws also provide penalties for abuse by falsifying emergency situations. In May 1955, a Poughkeepsie, New York woman was indicted by a grand jury after her refusal to relinquish a party line delayed a volunteer firefighter's effort to report a grass fire; the fire destroyed a shed and a barn. She was given a suspended sentence. In June 1970, a sixteen-year-old girl and a woman were charged after refusing to relinquish a party line to allow a distress call as three boys drowned in a pond in Walsenburg, Colorado.〔〕 By the 1980s, party lines were displaced in most localities as they could not support subscriber-owned equipment such as answering machines and computer modems. The electro-mechanical switching equipment required for their operation was rapidly becoming obsolete, supplanted by electronic and digital switching equipment. The new telephone exchange equipment offered vertical service code calling features such as call forwarding and call waiting, but often was incompatible with multi-party lines. In 1971, Southern Bell had announced plans for phase-out of party lines in North Carolina. In 1989, the Chesapeake and Potomac Telephone Company replaced party lines with private lines in Talcott, West Virginia, a rural area which once had as many as sixteen subscribers on one line. In 1991, Southwestern Bell set out to replace all of its party lines in Texas with private lines by 1995. Woodbury, Connecticut's independent telephone company abandoned its last party lines in 1991, the last in that state to do so. Party lines in the United States were ineligible for Universal Service Fund subsidies and telephone companies converted them to private lines to benefit from the subsidies. Universities also phased out the systems, which were once common in student dormitories. Illinois State University terminated its last party line in 1990.〔.〕 One of the last manual telephone exchanges with party lines in Australia was closed down in 1986 in the township of Collarenebri, where most town residents had a telephone number of only three digits, and to make a call outside the exchange area it was necessary to call the exchange to place a call. For rural residents, many were on a single telephone line identified by a number and a property name, for example one party line was called Gundabluie 1 line. Each party on that single line was identified by a letter, and so to call that party, the exchange would be called and the number asked for would be Gundabluie 1 S for example. The exchange rang a distinct ring down the Gundabluie 1 line, signalling the party's corresponding letter in Morse code. This distinctive ring would alert all parties on the line who the call was for. Three short rings signified the call was for the party with the S letter and so on. 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「Party line (telephony)」の詳細全文を読む スポンサード リンク
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