Area Code 602

North American area code 602 is a state of Arizona telephone area code that covers most of the city of Phoenix. It was one of the original area codes established in October 1947 and originally covered the entire state of Arizona until 1995 when area code 520 was established as the state's second area code. While Arizona's explosive expansion during the second half of the 20th century would have made a split necessary in any event, it was hastened by the demand for telephone lines created by the proliferation of fax machines, cell phones and dial-up Internet connections. Many states introduced new area codes during this time frame for much the same reason. Generally, greater Phoenix retained 602, except for some outer portions of Maricopa County that transferred to 520.

The creation of 520 was intended as a long-term solution. Within only three years, however, 602 came close to exhaustion once again. It was eventually decided that the Phoenix metropolitan area required multiple area codes. Initially, plans called for an overlay of 602 with another area code. However, overlays were a new concept at the time, and met with some resistance due to the requirement for ten-digit dialing and the fact that overlays make the location of phone numbers ambiguous. As a result, a three-way geographic split was chosen instead. The split became effective on April 1, 1999. The East Valley, the town of Paradise Valley (which goes as far west as 32nd St) as well as the city north of Union Hills and east of the 2000 E Grid, and everything from about 56th Street eastward, became 480. Most of the West Valley and the city west of 39th Ave north of Indian School to west of 63rd Ave from I-10 south, along with the city from north of Union Hills and west of the 2000 E Grid, became 623.

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