403 Area Code
Area code 403 is one of the original 86 area codes created by AT&T and the Bell System in 1947. It originally served the entire province of Alberta. In 1997, area code 403 was split, and some of the phone numbers had to be updated to area code 867 on that date. In 1999, area code 780 was created as an overlay to area code 403. Currently, the largest city it serves is Calgary, AB, and it overlaps coverage areas with area codes 587 and 780.