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Area codes 905, 289, and 365 are overlay area codes in the North American Numbering Plan (NANP) for southern Ontario, Canada. The plan area includes the Niagara Peninsula, Hamilton, Oshawa, and the suburban Greater Toronto Area. Area code 905 was assigned on October 4, 1993, as a split from area code 416. 289 was overlaid on June 9, 2001; since then, all local calls have required ten-digit dialling. On April 13, 2010, the Canadian Radio-television and Telecommunications Commission (CRTC) announced another overlay code for this area, 365. It became operational on March 25, 2013. The plan area surrounds the overlay area of the city of Toronto, having area codes 416, 647, and 437. It is bounded with area code 519 and 226 in the west, 705/249 in the north, 613/343 in the east, and New York State area code 716 on the eastern prong of the Niagara peninsula. The incumbent local exchange carrier for these area codes is Bell Canada, which acquired the remaining independent company ca. 1980. ==History== The 905 area code was once used as a block of alternate numbers for calls from the United States to Mexico (+52-5-...) in the days when overseas calls otherwise would have needed to be placed through a telephone operator. This use became obsolete with the widespread introduction of direct dial overseas calls and was completely abolished no later than February 1, 1991. Partly because of this prior usage of the number 905, area code 905 was the last of the "original-1947-format" area codes (that is, area codes with "0" () or "1" () for the middle digit, and 2-9 for the last digit) to be assigned. By October 1991, the numbering plan area (NPA) had been assigned to relieve exchanges in the Greater Toronto area--which, then as now, was Canada's largest toll-free calling zone. Automatic number identification (ANI) on the NPA's switching systems began transmission on October 11, 1992 for some central office codes. The area code entered service on October 11, 1993, and full conversion was achieved by January 1, 1994. Five years after its introduction, 905 was close to exhaustion far sooner than anticipated due to Canada's inefficient system of number allocation. Canada does not use number pooling as a relief measure. Each CLEC is assigned blocks of 10,000 numbers for every rate centre where it plans to offer service, no matter how small. While most rate centres don't need nearly that many numbers, a number is unavailable for reassignment elsewhere once assigned to a CLEC and rate centre. This resulted in thousands of wasted numbers, and the proliferation of cell phones, fax lines, and secondary phone lines for home dial-up Internet use only exacerbated this. By 1999, the CRTC had established an ad-hoc committee to study NPA relief planning for area code 905. A split of the 905 NPA was considered, with various options presented: * a geographic split by municipality (either two-way or three-way) * a geographic split of concentric rings around Toronto * re-aligning NPA boundaries (some areas retain 905, others acquire a new NPA); that is, a municipality and exchange split * a distributed overlay The overlay option was chosen because it would cause the least disruption; it would require no changes for existing customers in the 905 area. It would also be far easier to implement technically. Bell and the other carriers in the area were especially supportive of an overlay; they did not want to force their customers to have to change their numbers for the second time in less than a decade or force ''en masse'' reprogramming of cell phones. For the same reason, Toronto itself was overlaid with area code 647 (and later 437). The 289 NPA overlay was approved by the CRTC on August 15, 2000 (Order CRTC 2000-772). Earlier that month, Toufic Saliba, consultant and technical engineer at the Commission, directed the addition of area code 289 in the 905 area code region. In doing so, Saliba directed that all carriers put in place a 10-digit dialing plan for all local calls. In this order, the Commission directed Bell Canada to implement the 10-digit local dialing plan.〔(Order CRTC 2001-840 (copy archived February 3, 2004) )〕 289 came into service on April 7, 2001, and was in full operation by June 9, 2001. 905 officially became exhausted in November 2005. All new central office prefixes are assigned in NPA 289, as there are no longer any available prefixes in 905. Due to the fact that this is a large and rapidly growing region, area code 365 was assigned for further relief on March 25, 2013, and area code 742 has been set aside for further relief as the area is expected to exhaust by 2036 at current growth rates. 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「Area codes 905, 289, and 365」の詳細全文を読む スポンサード リンク
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