Телефонные коды региона Голден-Хорсшу, Онтарио (Канада)

Area codes in southern Ontario, Canada

Area codes 905, 289, 365, and 742 are telephone area codes in the North American Numbering Plan (NANP) for the Golden Horseshoe region that surrounds Lake Ontario in Southern Ontario, Canada. The numbering plan area (NPA) comprises (clockwise) the Niagara Peninsula, the city of Hamilton, the regional municipalities of Halton, Peel, York, Durham, and parts of Northumberland County, but excludes the City of Toronto. The four area codes form an overlay numbering plan for the same geographic region, where area code 905 was established in October 1993 in an area code split from area code 416. When 289 was overlaid on June 9, 2001, all local calls required ten digit dialing. On April 13, 2010, the Canadian Radio television and Telecommunications Commission (CRTC) introduced another overlay code, area code 365, which became operational on March 25, 2013. Area code 742 was added to the overlay on October 16, 2021. The numbering plan area surrounds the city of Toronto (area codes 416/647/437), leading locals to refer to the primarily suburban cities surrounding Toronto as "the 905" or "905 belt". It is bound by the 519/226/548 overlay area in the west, 705/249/683 in the north, 613/343 in the east, and Western New York State's 716/624 area on the eastern prong of the Niagara Peninsula. The incumbent local exchange carrier is Bell Canada.

The term the 905 or the 905 belt is used to describe the suburban areas of the Greater Toronto Area, while Toronto proper is referred to as the 416. The term 905er is often used pejoratively by Toronto residents to refer to suburban residents outside the city. Canadian rapper Maestro rendered homage to the area code in his song "416/905 (TO Party Anthem)"; "TO" (pronounced "T" "O") is an abbreviation or nickname locals use when referring to the city of Toronto. In June 2015, Maple Leaf Sports & Entertainment announced the formation of an NBA Development League team for the Toronto Raptors based in Mississauga called Raptors 905. The term has been used in the context of Canadian politics, where the 416 is a stronghold of Liberals and NDP, whereas the 905 (excluding Hamilton) historically had strong ties to the Progressive Conservative Party. The region has, however, backed opposition parties as a protest vote, including both the NDP in the 1990 provincial election and the Liberals in the 2003 provincial election, as a backlash to the incumbent government. In both cases, the opposition party was elected to government with strong backing of the 905 region. The 2011 federal election saw the 905 region become predominately represented by candidates of the Conservative Party of Canada, while one third of the 416 ridings were won by Conservatives, many through vote splitting between the Liberals and NDP. In the 2019 federal election, the Liberals successfully held all 25 ridings in the 416, which they won in 2015. However, the parties were fighting over control over the 905 as historically, winning the 905 is key to parties forming government and the region has become a political bellwether. In the end, most 905 ridings were won by the Liberals over the Conservatives. The Liberals ultimately beat the Conservatives and formed a minority government with the support of the 905.