North American Numbers Source-cited · ownership disclosed
Area code
858
In service
United States · since 1999

San Diego (northern/coastal)

Area code 858 serves northwestern San Diego County, California, including La Jolla and Poway. It split from area code 619 in 1999 and has formed an all-services overlay with 619 since 2018.

The essentials Numbering data · NumberResearch · as of 2026-09-18
Place
San Diego (northern/coastal)
Type
geographic
Status
in service
In service since
1999
Projected exhaust
2039 Q3

Status, dates and counts are read from NumberResearch (NANPA / CNAC / FCC records). Assignment records show initial assignees, not the carrier serving a number today.

A · Where it is

Where 858 is

Northwestern San Diego County, California..

Communities served wholly or partly by 858:

La JollaPowayRancho BernardoCarmel ValleyDel MarSolana Beach

Representative list of principal communities, not exhaustive.

B · Relationships

How it relates to other codes

The codes 858 was split from, spawned, or shares its area with. A split divides the map and changes some numbers; an overlay shares the same ground and changes none — what's the difference?

Split from · 1999 619 San Diego 858 was created on June 12, 1999 by a split of area code 619.
Overlay · 2018 619 San Diego Since June 2018, 858 and 619 form an all-services overlay covering the same inner San Diego County territory.
What's changing. All-services overlay with area code 619 since June 2018; ten-digit dialing is mandatory.
C · History

How 858 got here

1998-06-30
NANPA approved creation of area code 858 for northwestern San Diego County.
Source: Wikipedia
1999-06-12
Area code 858 introduced by a split of 619; a planned third code (935) was cancelled due to opposition.
Source: Wikipedia
2018-06
The 619/858 boundary was eliminated and both became an all-services overlay; ten-digit dialing became mandatory.
Source: Wikipedia
D · Capacity

How full it is

Prefixes assigned
577
Prefixes available
223
Thousands-blocks assigned
3,072

Prefix-assignment counts describe allocation to carriers, not how many individual numbers are in use. Full technical records: NumberResearch ↗.

Compare 858 with another code →
Sources
Wikipedia ↗
Area code 858
NumberResearch.org ↗
Live status, dates, assignment counts and exhaust forecast — data as of 2026-09-18 (CC BY 4.0).

Place, relationships and history above are compiled by North American Numbers from the sources listed and last checked 2026-09-18. A check date is not an expert review — see how this is made. Flag an error.