Area codes 450 and 579, Telephone numbering plan in Montreal suburbs, Canada.
Area codes 450 and 579 are telephone numbering zones serving suburban regions around Montreal, including Laval, Longueuil, Terrebonne, and Saint-Jean-sur-Richelieu. These codes connect millions of people across dozens of municipalities in the Greater Montreal area using ten-digit dialing.
The original area code 514 became overloaded as the greater Montreal region expanded, leading to the creation of 450 in 1998 to serve surrounding areas. A decade later, 579 was added in 2010 to handle the continued growth of telephone numbers across the suburbs.
Local residents commonly refer to the suburban areas by these codes as "les 450," creating a clear distinction in everyday speech between the island and outlying municipalities. This informal regional identifier has become part of the local vocabulary.
Calls between phone numbers with codes 450 and 579 require dialing all ten digits even when both are within the same local area. Emergency services like 911 maintain their short number format regardless of which code is in use throughout the region.
A small area in Ontario actually uses phone numbers from a Quebec-based exchange because Chute-à-Blondeau is geographically closer to the Quebec side. This cross-border arrangement shows how telephone numbering follows practical connectivity rather than official provincial boundaries.
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