Area code 403 serves southern Alberta, Canada, including Calgary, Lethbridge, Red Deer, and surrounding rural areas. Originally covering all of Alberta, it now shares the province with overlays 587, 825, and 368. Calgary is a key business and financial center, known for its ties to the energy sector, especially oil and gas. The city also has strong representation in engineering, tech, and aerospace. Red Deer and Lethbridge add strength in agriculture, manufacturing, and healthcare. 403 is one of Canada’s older and more established codes, often associated with local heritage and prestige. A 403 number signals deep regional ties and is especially valuable for energy firms, logistics providers, and tradespeople operating across Alberta. Whether you're targeting city clients or rural communities, it’s a powerful symbol of southern Alberta identity.