Area Code Atlas

NANP-Split of the 602 (Arizona) Numbering Plan Area (NPA) and the Addition of the 480 and 623 NPA's

NPA 623 split from 602

Area code 623 was created on March 1, 1999, as part of a three-way split of area code 602. The new code served the West Valley of the Phoenix metropolitan area, while 602 was retained for central Phoenix.

Introduction of overlay area code 623 in Phoenix West Valley

On April 1, 1999, area code 623 was added as an overlay for the West Valley region of Phoenix, Arizona, alongside 480 and 602, requiring ten-digit dialing.

Permissive dialing begins for new area codes 480 and 623

Permissive dialing of the new area codes 480 and 623 began on April 1, 1999, allowing callers to use either the old 602 or the new codes during the transition period.

Urgent reminder to update networks for the 602 NPA Split in Phoenix, Arizona with the new 623 and 480 NPAs

Permissive ten-digit dialing begins in 602 and 623

A six-month permissive ten-digit dialing period began in area codes 602 and 623 ahead of the overlay activation. Ten-digit dialing was already mandatory in 480.

Boundary elimination overlay for 602, 480, and 623 approved and planned

The Arizona Corporation Commission approved a plan on November 9, 2021, to eliminate area code boundaries among 602, 480, and 623, creating a unified overlay complex for the entire Phoenix metropolitan area to address number exhaustion. This plan was followed by activation of the overlay in 2023.

NPA 480, 602 and 623 Boundary Elimination Overlay (Arizona)

Permissive ten-digit dialing for 602 and 623

A permissive ten-digit dialing period for area codes 602 and 623 began on February 11, 2023, as part of the transition to the new overlay complex in the Phoenix area.

Overlay complex activated for 602, 480, and 623 in 2023

The overlay complex for area codes 602, 480, and 623 was activated on September 12, 2023, removing boundaries within the Phoenix metropolitan area and requiring ten-digit dialing throughout the region, allowing new central office codes to be assigned across the entire area.

Arizona overlay complex implementation and mandatory 10-digit dialing

The overlay complex involving area codes 602, 480, and 623 was implemented in September 2023, making ten-digit dialing mandatory across the Phoenix metropolitan area, following relief planning and regulatory approval in 2021.