Area code 623 serves the western suburbs of Phoenix, Arizona, including Glendale, Peoria, and Avondale. It was created in 1999 as a split from area code 602 to accommodate the region’s rapid growth. As a part of the Phoenix metropolitan area, 623 is associated with suburban expansion, sports venues, and growing business parks. The code reflects the dynamic development of the West Valley. With overlays in the Phoenix area, ten-digit dialing is standard. 623 is a modern code tied to Arizona’s booming growth.