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Area codes 416, 647, and 437 are telephone area codes serving the single rate centre of Toronto, Ontario, Canada. The incumbent local exchange carrier in the 416/647/437 territory is Bell Canada. Almost all Toronto Bell Canada landlines are in area code 416, with 647 numbers allocated disproportionately to a growing mobile telephone market and to competitive local exchange providers (such as cable and voice-over-IP gateways). Local numbers are portable, with few limited exceptions for specific services such as pocket pagers. Demand for 416 numbers for mobile, foreign exchange and voice over IP service in the "905 suburbs" (Durham, Peel, and York regions) has made the numbers valuable as their local calling area is a superset of that of a suburban number.〔http://www.torontolife.com/informer/random-stuff-informer/2013/02/14/toronto-area-code-stereotypes-guide/〕 ==History== The main area code, 416, was one of the 86 original area codes introduced in 1947.〔(【引用サイトリンク】title=LincMad's 1947 Area Code List )〕 It originally covered most of the populous Golden Horseshoe region in southern Ontario, from Colborne to Niagara Falls to Kitchener-Waterloo. It was almost completely surrounded by Ontario's other area code, 613. Ontario and Quebec were the only provinces to be assigned multiple area codes at the outset. Toronto numbers, originally six digits (2L+4N) with named exchanges, were lengthened to seven (2L+5N) in the 1950s to accommodate direct distance dialling.〔(【引用サイトリンク】title=Phone exchange names once defined neighbourhoods )〕 The 416 area code has been split twice. The western portion of 416 (including Kitchener) and the northern portion of 613 were assigned area code 519 in 1953. Despite the Greater Toronto Area's rapid growth, this configuration remained for 40 years. By the late 1980s, however, 416 was close to exhaustion due to the GTA's continued growth and Canada's inefficient number allocation system. Canada does not use number pooling as a relief measure. Each competing carrier is assigned 10,000-number blocks (roughly corresponding to a single prefix) in each rate centre where it plans to offer service, regardless of their actual subscriber count. While most rate centres don't need nearly that many numbers to serve their customers, a number can't be allocated elsewhere once assigned to a carrier and rate centre. This resulted in thousands of wasted numbers, an issue exacerbated at the time by a proliferation of cell phones, pagers and fax machines. As a solution, the 416 territory was reduced to its current size in 1993, when area code 905 was assigned to most of Toronto's suburbs; it almost completely surrounds 416. This made 416 coextensive with Metro Toronto (York, East York, North York, Etobicoke, Scarborough and Old Toronto). While the GTA would have likely needed another area code at some point given its explosive growth, it is possible that the 905 split would have been delayed had it been possible to reallocate numbers from the GTA's smaller rate centres to Toronto. With the amalgamation of Metro Toronto into the "megacity" of Toronto in 1998, 416 became the only Canadian area code to serve just one rate centre and just one city. Many of Canada's larger cities are split between multiple rate centres that have never been amalgamated. Toronto is an exception; it has been a single rate centre—by far, Canada's largest—since 1977, with the merger of historical exchanges Agincourt, Don Mills, Islington, New Toronto, Scarborough, West Hill, Weston, and Willowdale into the Toronto exchange.〔(【引用サイトリンク】title=Toronto telephone exchange geography )〕 The 1993 split had been intended as a long-term solution for Canada's largest toll-free calling zone. Within five years, 416 was once again close to exhaustion due to Toronto's rapid growth, as well as the aforementioned number allocation problem. Splitting Toronto between two area codes—a solution adopted in the United States for cities like New York City, Chicago and Los Angeles—was ruled out because of the area's high population density and lack of a suitable boundary along which to split. Another option was an overlay area code covering the same area as 416. Overlays were a new concept at the time, and somewhat controversial due to the requirement for ten-digit dialling. However, Bell and other telephone companies pressed for an overlay. They wanted to spare their customers the expense and burden of having to change their numbers, which would have required ''en masse'' reprogramming of cellular telephones. Ultimately, it was decided to implement an overlay. On 5 March 2001, 416 was overlaid with area code 647, Canada's first overlay code. The implementation of 647 made ten-digit dialling mandatory in Toronto. However, within a decade, both 416 and 647 were close to exhaustion. A new overlay area code, 437, commenced operation on March 25, 2013. This effectively allocates 24 million numbers to one city of 2.5 million people, but a fourth area code (387) has been reserved for Toronto's future use.〔 However, under current projections it will not need to be implemented until 2034 at the earliest.〔http://www.nanpa.com/pdf/NRUF/October_2014_NPA_Exhaust_Projections.pdf〕 Since the implementation of 647, overlays have become the preferred solution for area code relief in Canada, as they allow carriers an easy workaround for the number allocation problem. As of 2014, seven-digit dialling has been broken in most of the country. 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 416, 647, and 437」の詳細全文を読む スポンサード リンク
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