|Year||Area Code||Serving Area|
|October 1947||213||All of Los Angeles County|
|1957||805||Ventura, Santa Barbara, San Luis Obispo, Bakersfield, Northern L.A. County (former 213)|
|1984||818||San Gabriel Valley, San Fernando Valley (former 213)|
|1991||310||Western, Eastern, & Southern L.A. County (former 213)|
|1992||909||Riverside, San Bernardino (former 714)|
|January 1997||562||Eastern L.A. County, Long Beach (former 310)|
|June 1997||626||San Gabriel (former 818)|
|June 1998||323||Los Angeles (former 213)|
|February 1999||661||Northern L.A. County including the Santa Clarita and Antelope Valleys (former 805)|
|July 2006||424||Overlay for Western L.A. County, Catalina Island (added to 310 region)|
|May 2009||747||Overlay for San Fernando Valley/West-Central L.A. County (added to 818 region)|
The former telephone company GTE (merged into Verizon) once inadvertantly published a telephone directory for Sierra Madre listing no home numbers.
In 1958, due to increased consumer demand for individual telephone numbers, the telephone company began phasing out old exchange names for all numeric telephone numbers or "All Number Calling" (pretty much gone by 1963). These old exchange names are remembered in Glenn Miller’s song PEnnsylvania 6-5000 and Elizabeth Taylor’s movie BUtterfield-8.
List of numbers for Los Angeles County gleaned from exchange names collected by the Telephone EXchange Name Project