Area code 403

Area code 403 is a telephone area code in the Canadian province of Alberta, encompassing the southern third of the province, including the Calgary area. It is one of the original 89 area codes assigned in 1947 in the contiguous United States and the then nine provinces extent of Canada.

Prior to October 21, 1997, the 403 area code encompassed the whole province of Alberta, the Yukon and the western half of the Northwest Territories, reaching more than one ninth of the circumference of the planet from the 49th Parallel to the North Pole. The territories were given their own separate area code, 867, in 1997. On January 25, 1999, the northern two-thirds of Alberta, including Edmonton, was split into the new area code 780. Generally, everything from Red Deer and Lacombe southward stayed in 403. Permissive dialing of 403 continued across the province until May 18, 1999.

Optional provincewide 10-digit dialing began on June 23, 2008 and became mandatory on September 12, 2008. This change was done to accommodate area code 587, which had been implemented as a provincewide overlay. On September 20, 2008; Telus Mobility began assigning 587 numbers to new customers in Calgary and Edmonton.

The incumbent local exchange carrier (LEC) in 403 is Telus; prior to 1997, the larger 403 included EdTel (Edmonton Telephones, now part of Telus) and Northwestel as incumbent LECs. Prior to 1990, Telus was known as Alberta Government Telephones, and was a department of the provincial government.

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