Area Code Atlas

NPA 310 split from 213

In 1991, area code 310 was created from a split of 213, assigning West Los Angeles and the South Bay to the new code.

NPA 310 split from 213

Area code 310 was created on November 2, 1991, when most of the western and southern portions of the old 213 region were assigned to the new code. This split reduced the coverage of 213 and established 310 as a distinct area code for the Westside and South Bay regions of Los Angeles County, serving a small portion of Ventura County and Santa Catalina Island.

NANP-OVERLAY OF 310 (CALIFORNIA) NUMBERING PLAN AREA (NPA)

NANP-SPLIT OF 310 (CALIFORNIA) NUMBERING PLAN AREA (NPA)

Extraordinary NPA-Specific Conservation Procedures for 310, 415, 619 and 714 NPAs (California)

NPA 562 split from 310

On January 25, 1997, area code 310 was split, creating area code 562 for much of southeastern Los Angeles County and parts of northern Orange County, including Long Beach and Whittier. The split was implemented after an earlier plan for an overlay was abandoned.

NANP-Overlay of 310 (California) Numbering Plan Area (NPA) with 424 NPA

310 NPA Splits, Creating 424 NPA (California)

NPA 424 overlay on 310 announced

NPA 424 to Overlay NPA 310 (California)

Permissive 1+10-digit dialing begins for 310/424 overlay

On December 31, 2005, customers in the 310 and 424 area codes began permissive dialing of 1 + area code + seven-digit number for calls between area codes, including calls between 310 and 424. This transition prepared callers for the upcoming overlay and mandatory ten-digit dialing.

NPA 424 overlays 310

Area code 424 was introduced as an overlay to the entire 310 region on July 26, 2006, marking California's first area code overlay. The overlay allowed new numbers to be assigned with the 424 code in the same geographic area as 310. This change affected West Los Angeles and South Bay, Los Angeles County, CA.

Mandatory 1+10-digit dialing for 310/424 overlay

Beginning July 26, 2006, mandatory 1 + area code + seven-digit dialing was required for all calls within the 310 and 424 area codes, coinciding with the implementation of the 424 overlay.