Area codes 450, 579, and 354 are telephone area codes in the North American Numbering Plan in the Canadian province of Quebec, encompassing the off-island suburbs of Montreal, as well as the rest of the Montérégie region southward to the border with New York state. Among the cities in the numbering plan area are Laval, Longueuil, Terrebonne, Saint-Jean-sur-Richelieu, Brossard, Repentigny, Saint-Jérôme, Granby, Blainville and Saint-Hyacinthe.
Area code 450 is also shared by several small communities in an adjacent part of Ontario: some landline customers in Chute-à-Blondeau (East Hawkesbury), near Pointe-Fortune use numbers from the Rigaud exchange 451.