Area codes 415 and 628 aretelephonearea codes in theNorth American Numbering Plan (NANP) for the city ofSan Francisco and its northern suburbs inMarin County (across theGolden Gate), and the northeast corner ofSan Mateo County in the U.S. state ofCalifornia. Area code 415 was one of the eighty-sixoriginal North American area codes established in 1947, but modified in geographic configuration later. Area code 628 was assigned in 2015 to form anoverlay in that numbering plan area in mitigation of central office prefix exhaustion.
When theAmerican Telephone and Telegraph Company (AT&T) introduced the first nationwidetelephone numbering plan forOperator Toll Dialing in 1947, the state ofCalifornia was divided into three numbering plan areas (NPAs) arranged as geographical zones in the southern part, the central part, and the northern part of the state.[1] Area code 415 was assigned to central California, south ofarea code 916, and north ofarea code 213. It stretched fromSacramento in the north toBakersfield in the south.[2]
In 1950, the boundaries of the numbering plan area were redrawn to produce a division of the northern and central parts along a north–south-running dividing line. Numbering plan area 415 became the coastal region from theNorth Coast to theOregon border, while 916 was redrawn to comprise the northeastern corner of the state.[3] As part of this realignment, Sacramento was renumbered from area code 415 to 916, and Bakersfield to 213.
With the preparations for nation-widedirect distance dialing (DDD) in the early 1950s,area code 318 was temporarily used in the San Francisco area, initially by customers inEnglewood, New Jersey, participating in the first customer trials to reach the city, as well as some areas north of theGolden Gate.[4] 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 converted to anoverlay complex by addingarea code 628 to the same service area,[9] makingten-digit dialing mandatory in the area, with prefix1 from landlines.[10]
| North:707/369 | ||
| West: Pacific Ocean,808 | 415/628 | East:510/341,925 |
| South:650 | ||
| Hawaii area codes:808 | ||