Area codes 819, 873, and 468 are overlay telephone area codes in the North American Numbering Plan (NANP) for central and western Quebec, Canada, including the Quebec portion of the National Capital Region, and the Hudson Strait and Ungava Bay coastlines of Quebec. Major cities in the territory include Gatineau, Sherbrooke, Trois-Rivières, Drummondville, Shawinigan, Victoriaville, Rouyn-Noranda, Val-d'Or, Magog and Mont-Laurier.

The incumbent local exchange carriers for the numbering plan area are Bell Canada, Bell Aliant, Telus, as well as Télébec and other independent companies. From 1992 to 1997, Northwestel was also an incumbent carrier in 819, as it included former Bell Canada areas in the Northwest Territories.

Ontario and Quebec were the only Canadian provinces that received assignments of multiple area codes from the American Telephone and Telegraph Company (AT&T) when the original North American area codes were created in 1947.

The eastern part of Quebec received area code 418, while the western part, from the US border to Hudson Strait, was assigned area code 514. After assignment of area code 819 in 1956, a 1957 flash cut split the 514 area into three segments.^{[citation needed]} The southern region (including Montreal) retained 514; the middle region received 819, and the northern region, which had no telephone services, was added to 418.

Area code 819 thus bordered area code 613 and the new area code 705 in Ontario, area code 418 in the east and the north of Quebec, and the remainder of area code 514 in the south of Quebec.

When telephone service was introduced in the eastern Northwest Territories (most of which is now the territory of Nunavut, created in 1999), in Frobisher Bay in 1958, Bell Canada nominally made it part of area code 418. In the 1960s and the 1970s, telephone service was introduced by Bell Canada at other locations in the eastern Northwest Territories and along the Quebec Arctic coastline, as well as by Sotel, an independent company, in the James Bay region. Those non-diallable locations also became part of area code 418.

In the late 1970s, the northern parts of area code 418 served by Sotel and Bell along James, Hudson and Ungava Bays and Hudson Strait, as well as the eastern Northwest Territories, were assigned to area code 819 as exchanges in that area began to receive direct distance dialling. Thus, area code 819 now also bordered area code 709 of Newfoundland in the Torngat Mountain area and area code 403 where Bell Canada and Northwestel service areas met, as well as area code 204 (Manitoba) and area code 807 (northwestern Ontario). Also, from the late 1970s to 1997, area code 819 extended one eighth of the way around the world, from the 45th parallel north at Stanstead, Quebec, to the North Pole, including much of the Northwest Territories along with most of western Quebec. Northwestel used Alberta's area code 403 for its services in Yukon and the Northwest Territories.

In 1997 and 1998, the portions of 819 in the Northwest Territories, as well as the portions of 403 in the Northwest Territories and Yukon, were transferred to area code 867, which was newly created to unite all of the Canadian territories, including Nunavut. Area code 819 was cut back to western Quebec, and area code 403 was reduced to serve only Alberta. Thus, borders with area codes 403, 204, and 807 were replaced with the single border on area code 867. Area code 514 was split shortly afterward, which changed area code's 819's border with 514 to a boundary with Area code 450, the new area code for the off-island suburbs of Montreal.