Area codes 415 and 628


Area codes 415 and 628 are telephone area codes in the North American Numbering Plan for the city of San Francisco and its northern suburbs in Marin County, and the northeast corner of San Mateo County.

History

When the North American Numbering Plan was installed by AT&T for Operator Toll Dialing in 1947, the state of California was divided into three numbering plan areas arranged as geographical zones in the southern part, the central part, and the northern part of the state. Area code 415 was assigned to central California, south of area code 916, and north of area code 213. It stretched from Sacramento in the north to Bakersfield in the south.
In 1950, the numbering plan area boundaries were redrawn to produce a division of the northern and central parts along a north-south dividing line. Numbering plan area 415 became the coastal region from the North Coast to the Oregon border, while 916 was redrawn to comprise the northeastern corner of the state. As part of this realignment, Sacramento was renumbered from area code 415 to 916, and Bakersfield to 213.
With the preparations for nation-wide direct distance dialing in the early 1950s, area code 318 was temporarily used in the San Francisco area, initially by customers in Englewood, New Jersey, participating in the first customer trials to reach the city, as well as some areas north of the Golden Gate. In 1953, the entire Bay Area was "reunited" in using area code 415.
Area code 415 has been split three times due to the Bay Area's rapid economic growth and demand for telecommunication services:
On February 21, 2015, the numbering plan area was transitioned to an overlay plan by adding area code 628 to the same service area for new numbers, making ten-digit dialing mandatory in the area, with eleven-digit dialing necessary from landlines. Until then, 415 had been one of the few urban area codes not to be overlaid, making San Francisco one of the largest cities where seven-digit dialing was still possible.

Service area

City and County of San Francisco

Dillon Beach and Tomales are in area code 707.

San Mateo County