Area code 403 is one of the original area codes established in 1947 and originally covered the entire province of Alberta, Canada. Today, it primarily serves southern Alberta, including Calgary, Lethbridge, and Medicine Hat. Due to rapid population growth and increased demand for phone numbers, area codes 587, 825, and 368 were added as overlays. Calgary, the economic hub of the region, is known for its energy sector, particularly oil and gas, and for hosting the famous Calgary Stampede. Despite the overlays, 403 remains a legacy code and a symbol of southern Alberta’s identity and history.