Area Code Overview

Area code 858 is a geographic telephone area code in California that went into service on June 12, 1999. The geographic regions covered by this area code overlay has a population of approximately 2,038,712.

Overlay and Dialing Rules

Area Code: 858
State: California
Type: General Purpose Code
In Service Date: June 12, 1999
Overlay Complex: 619/858
Local Dialing Plan: This area requires you to dial 1 and the area code when calling locally.

Estimated Number of Assigned Phone Numbers in Area Code 858

This area code is ranked 200th out of 363 nationwide in estimated assigned phone numbers. Within the state territory it serves, it is ranked 26th out of 39.

4,529,000

Estimated Service-Type Mix of Assigned Phone Numbers in Area Code 858

Total assigned 4,529,000

Wireless

1,448,000 assigned

31.97%

Wireline and VoIP

2,633,000 assigned

58.14%

Other / Unclassified

448,000 assigned

9.89%

Estimated Share of Wireless Numbers Originally Assigned to Each Carrier in Area Code 858

Estimated assigned wireless phone numbers: 1,448,000

Numbers may later be ported to another carrier, but this chart reflects original number assignment, not current subscriber share.

AT&T Wireless 548,000 (37.85%)

T-Mobile 451,000 (31.15%)

Verizon Wireless 449,000 (31.01%)

Estimated Share of Wireline and VoIP Numbers Originally Assigned to Each Carrier in Area Code 858

Estimated assigned wireline and VoIP phone numbers: 2,633,000

AT&T 1,063,000 (40.37%)

Onvoy 528,000 (20.05%)

Lumen 222,000 (8.43%)

Bandwidth 219,000 (8.32%)

MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA 95,000 (3.61%)

Comcast Business 93,000 (3.53%)

Spectrum 79,000 (3.00%)

Peerless Network 68,000 (2.58%)

TIME WARNER CBL INFO SVCS (CA) DBA TIME WARNER CAB 67,000 (2.54%)

PAETEC ITEL, LLC 58,000 (2.20%)

Commio 54,000 (2.05%)

Telnyx 43,000 (1.63%)

Other / Unclassified Assigned Numbering in Area Code 858

Estimated assigned other or unclassified phone numbers: 448,000

TELEPORT COMMUNICATIONS AMERICA, LLC - CA 199,000 (44.42%)

U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 69,000 (15.40%)

NORTH COUNTY COMMUNICATION CORPORATION - CA 60,000 (13.39%)

AMERICAN MESSAGING SERVICES, LLC 40,000 (8.93%)

FRACTEL, LLC 34,000 (7.59%)

SPOK, INC. 20,000 (4.46%)

HD CARRIER LLC 13,000 (2.90%)

TON80 COMMUNICATIONS, LLC 8,000 (1.79%)

EXIANT COMMUNICATIONS LLC 2,000 (0.45%)

FIVE9, INC. 1,000 (0.22%)

IP HORIZON LLC 1,000 (0.22%)

WAVENATION, LLC 1,000 (0.22%)

Cities and Towns in Area Code 858

Alpine, California Campo, California Chula Vista, California Coronado, California Del Mar, California Dulzura, California El Cajon, California Jacumba, California La Jolla, California La Mesa, California National City, California Pine Valley, California Poway, California Rancho Santa Fe, California San Diego, California

These geographic regions are also served by area code 619.

How These Figures Were Built

These figures are estimates based on public phone-number assignment records. They are meant to show the likely mix of assigned phone numbers associated with area code 858, not live customer counts.

Some providers may have assigned phone numbers tied to this area code even if they do not actively market or sell service locally. These figures reflect public number-assignment records, not confirmed local service availability.

They also do not reflect number portability at the individual phone-number level, so some numbers may now be used on a different network or by a different provider than the original assignment records suggest.

Population data and locality matching provided by GeoNames.

Last refreshed: April 15, 2026 6:22 pm