Area codes 602, 480, and 623

Area codes 602, 480, and 623 are telephone area codes in the North American Numbering Plan (NANP) for most of the Phoenix metropolitan area in the U.S. state of Arizona.

Area code 602 is the oldest area code in Arizona, and was assigned in 1947 for the entire state. Under pressure from population growth and new telecommunications services, the numbering plan area (NPA) was reduced twice in five years in the 1990s. In 1995, the state outside metropolitan Phoenix was split off with area code 520. In 1999, a second split created two new area codes: 480 in the East Valley and 623 in the West Valley. Metro Phoenix continued to be a single rate center after the split, so that calls between the three area codes were generally local calls.

By the early 2020s, NPAs 480 and 602 were facing exhaustion within the decade, but 623 continued to have hundreds of unassigned central office codes and was not expected to exhaust for the foreseeable future. As a result, in 2021, the Arizona Corporation Commission converted the 602, 480, and 623 numbering plan areas into an overlay complex for the entire Phoenix area by removing the involved NPA boundaries in 2023. This made ten-digit dialing mandatory across the Valley; it was already required in 480.

History

Early history and split of 602

When the American Telephone and Telegraph Company (AT&T) created the first nationwide telephone numbering plan in 1947, Arizona was designated as a single numbering plan area (NPA), and received a single area code, 602, of the original 86 area codes for routing telephone toll calls into the state.