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In conventional landline telephony, a non-dialable toll point or toll station was a lone station or line serving a rural subscriber many miles from the nearest central office. As it had no home telephone exchange and therefore no local calling area, all connections were obtained manually from the long distance operator.〔(【引用サイトリンク】title=The inward operator (John R. Covert; Robert E. Seastrom; Bill Chiarchiaro; Gabe M Wiener) )〕 These toll stations were one of multiple categories of non-dialable points which could only be reached with assistance from the inward operator at destination. Other non-dialable points included locations reachable only by some form of two-way radio and specific categories of manual service. As manual services are replaced by automated infrastructure and satellite telephony now reaches the most distant points on the globe, truly non-dialable points are becoming rare. == Toll stations == To reach remote rural locations, telephone companies have been created with as little as one subscriber (the Methodist Episcopal Corporation, established in the 1940s to interconnect a Methodist church in Carmanville, Ontario to Bell Canada's long distance network, was taken over by Bell in 1970).〔Michael Dawber, Fri, 01 Aug 1997, http://ourwebhome.com/TENP/Historical.html〕 A similar service was provided in North America using toll stations or "ring downs", individual subscribers who were connected over many miles of landline directly to AT&T long distance with no local calling area. Reachable only with operator assistance, these served points like Deep Springs College in Deep Springs, California (whose telephone number for much of the 1980s remained "Deep Springs Toll Station #2"), far corners of the Nevada or California deserts and a few individual ranches in very remote corners of the Texas Panhandle.〔 In Canada, regional incumbent local exchange carriers (such as Telus in Alberta, MTS in Manitoba or Bell Canada in Ontario and Quebec) provided operator assistance to complete inbound calls to non-dialable points.〔http://www.mts.ca/tariffs/pdf/AccessItem10.pdf and http://www.mts.ca/tariffs/pdf/AccessItem41.pdf in MTS ILEC tariff〕 Local telephone companies were installing toll stations in distant rural areas as recently as the 1970s.〔http://www.company-histories.com/Nevada-Bell-Telephone-Company-Company-History.html〕 While many of these points have subsequently been moved to conventional dial exchanges, in 1999 just over six hundred toll stations were still in service in the North American Numbering Plan. Many were a lone party line serving some remote hamlet too small for its own telephone exchange.〔(【引用サイトリンク】title=Privateline.com Telephone History: Toll Stations )〕 In 1999, more than half of the remaining toll stations were in Canada, with Quebec and Newfoundland the largest users. The remaining US toll stations mostly served rural Nevada, with a handful in California and Oregon.〔 A request for "TinyVille Toll Station #2" would require the operator call the inbound operator (NPA+121) or a special ringdown operator (NPA+181) at destination,〔(【引用サイトリンク】title=The Official Phreaker's Manual )〕 who would ring the one line to "TinyVille" with a specific pattern to signal the second subscriber to answer. The system created operator confusion and was incompatible with equipment based on auto-dial modems, such as automated teller machines. Nevada Bell and GTE replaced the last of their Nevada toll stations with seven-digit dial service in 2001.〔(【引用サイトリンク】title='Connect me to Cosgrave No. 3, please' )〕 These points originally appeared directly in national AT&T or Bellcore routing tables; each would have its own V and H co-ordinates (as toll calls are billed by distance)〔http://www.crtc.gc.ca/eng/archive/2001/O2001-719.htm〕 and a non-dialable number for billing records (initially within the geographic area code, although often in an invalid format like 702-012-3456). The list of non-dialable points was later maintained by NANPA (in the US)〔http://www.nationalnanpa.com/pdf/newsletters/nanpa_april_may.PDF〕 and CNAC (in Canada). A pair of area codes (886 and 889), created post-1995 and abolished on July 1, 2003,〔(【引用サイトリンク】title=World Telephone Numbering Guide )〕 was used by NANPA and CNAC to list each non-dialable toll point as a rate centre and exchange (a block of 10000 numbers with an associated geographic pair of V/H co-ordinates for billing distance calculation); these codes have since been reclaimed for use as future toll-free numbers. 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「Non-dialable point」の詳細全文を読む スポンサード リンク
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