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The push-button telephone is a telephone that uses buttons or keys for dialing a telephone number to place a call to another telephone subscriber. Western Electric experimented as early as 1941 with methods of using mechanically activated reeds to produce two tones for each of the ten digits and by the late 1940s such technology was field-tested in a No. 5 Crossbar switching system in Pennsylvania.〔Bell Telephone Laboratories, ''A History of Engineering and Science in the Bell System - Switching Technologies (1975, AT&T)〕〔(Push. Click. Touch. - History of the Button - 1963: Pushbutton Telephone ) - December 11, 2006〕 But the technology proved unreliable and it was not until long after the invention of the transistor when push-button technology matured. On 18 November 1963, after approximately three years of customer testing, the Bell System in the United States officially introduced dual-tone multi-frequency (DTMF) technology under its registered Touch-Tone mark. Over the next few decades touch-tone service replaced traditional pulse dialing technology and it eventually became a world-wide standard for telecommunication signaling. Although DTMF was the driving technology implemented in push-button telephones, some telephone manufacturers used push-button keypads to generate pulse dial signaling. Before the introduction of touch-tone telephone sets, the Bell System sometimes used the term ''push-button telephone'' to refer to key system telephones, which were rotary dial telephones that also had a set of push-buttons to select one of multiple telephone circuits, or to activate other features. ==History== The concept of the use of push-buttons in telephony originated around 1887 with a device called the micro-telephone push-button, but it was not an automatic dialing system as understood later. This use even predated the invention of the rotary dial by Almon Brown Strowger in 1891.〔(The New York Times - "When Dials Were Round and Clicks Were Plentiful" )- by Catherine Greenman, October, 1999〕 The Bell System in the United States relied on manual switched service until 1919, when it reversed its decisions and embraced dialed, automatic switching. The 1951 introduction of direct distance dialing required automatic transmission of dialed numbers between distant exchanges, leading to use of inband multi-frequency signaling within the Long Lines network while individual local subscribers continued to dial using standard pulses. As direct distance dialing expanded to a growing number of communities, local numbers (often four, five or six digits) were extended to standardized seven-digit named exchanges. A toll call to another area code was eleven digits, including the leading 1. In the 1950s, AT&T conducted extensive studies of product engineering and efficiency and concluded that push-button dialing was preferable to rotary dialing.〔(Britannica. - Call number dialing )〕 After initial customer trials in Connecticut and Illinois, approximately one fourth of the central office in Findlay, Ohio, was equipped in 1960 with touch-tone digit registers for the first commercial deployment of push-button dialing, starting on 1 November 1960.〔AT&T, J.G. Lindsay (ed.), December 1960, ''Touch-Tone Phones Offered'', Long Lines, Vol. 40 (5), 25.〕〔http://visitfindlay.com/about/findlays-bicentennial/〕 On 22 April 1963 President John F. Kennedy opened the World's Fair by keying ''1963'' on a touch-tone telephone in the Oval Office, ushering in the era of the pushbutton telephone. On November 18, 1963, the first electronic push-button system with touch-tone dialing was offered by Bell Telephone to customers in the Pittsburgh area towns of Carnegie and Greensburg, Pennsylvania.〔〔(Engineering Pathway - Bell Telephone introduces push button telephone ) - by Alice Agogino - November 18, 2009〕 This phone, the Western Electric 1500, had only ten buttons. In 1968 it was replaced by the twelve-button model 2500, adding the asterisk or star ( *) and pound or hash (#) keys. The use of tones instead of dial pulses relied heavily on technology already developed for the long line network, although the 1963 touch-tone deployment adopted a different frequency set for its dual-tone multi-frequency signaling. Although push-button touch-tone telephones made their debut to the general public in 1963, the rotary dial telephone still was common for many years. In the 1970s the majority of telephone subscribers still had rotary phones, which in the Bell System of that era were leased from telephone companies instead of being owned outright.〔http://www.irememberjfk.com/mt/when_we_dialed_telephone_numbe.php〕 Adoption of the push-button phone was steady, but it took a long time for them to appear in some areas.〔(I Remember JFK - Push-Button Telephones )〕 At first it was primarily businesses that adopted push-button phones.〔(Wise Geek - What is a Touch Tone Telephone? )〕 By 1979, the touch-tone phone was gaining popularity,〔 but it wasn't until the 1980s that the majority of customers owned push-button telephones in their homes; by the 1990s, it was the overwhelming majority. Some exchanges no longer support pulse-dialing〔 or charge their few remaining pulse-dial users the higher tone-dial monthly rate as rotary telephones become increasingly rare.〔(TimesDaily.com - Advances make many items close to obsolete ) - by Tom Smith & Bernie Delinski - October 14, 2009 - Retrieved February 10, 2010〕〔The Free Lance-Star - Aug 12, 1994, by Michael Zitz, page 1 - (Rotary phone users in info highway's slow lane )〕〔(Sacramento Business Journal - Rotary phones ring true for few - all but gone from workplace ) - March 9, 2001〕 Dial telephones are not compatible with some modern telephone features, including interactive voice response systems, though enthusiasts may adapt pulse-dialing telephones using a pulse-to-tone converter. 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「Push-button telephone」の詳細全文を読む スポンサード リンク
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