Area Code Overview

Area code 820 is a geographic telephone area code in California that went into service on June 30, 2018. The geographic regions covered by this area code overlay has a population of approximately 1,935,410.

Overlay and Dialing Rules

Area Code: 820
State: California
Type: General Purpose Code
In Service Date: June 30, 2018
Overlay Complex: 805/820
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 820

This area code is ranked 334th out of 363 nationwide in estimated assigned phone numbers. Within the state territory it serves, it is ranked 36th out of 39.

752,000

Estimated Service-Type Mix of Assigned Phone Numbers in Area Code 820

Total assigned 752,000

Wireless

351,000 assigned

46.68%

Wireline and VoIP

326,000 assigned

43.35%

Other / Unclassified

75,000 assigned

9.97%

Estimated Share of Wireless Numbers Originally Assigned to Each Carrier in Area Code 820

Estimated assigned wireless phone numbers: 351,000

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

AT&T Wireless 189,000 (53.85%)

T-Mobile 109,000 (31.05%)

Verizon Wireless 52,000 (14.81%)

Optimum Mobile 1,000 (0.28%)

Estimated Share of Wireline and VoIP Numbers Originally Assigned to Each Carrier in Area Code 820

Estimated assigned wireline and VoIP phone numbers: 326,000

Onvoy 180,000 (55.21%)

Spectrum 51,000 (15.64%)

Commio 28,000 (8.59%)

Bandwidth 24,000 (7.36%)

NUSO 9,000 (2.76%)

Peerless Network 7,000 (2.15%)

AT&T 6,000 (1.84%)

Telnyx 5,000 (1.53%)

TERRA NOVA TELECOM INC. 4,000 (1.23%)

Vonage 4,000 (1.23%)

Twilio 2,000 (0.61%)

ADVANCED TELECOM SOLUTIONS, LLC 1,000 (0.31%)

Other / Unclassified Assigned Numbering in Area Code 820

Estimated assigned other or unclassified phone numbers: 75,000

FRACTEL, LLC 44,000 (58.67%)

SHELCOMM 10,000 (13.33%)

TELEPORT COMMUNICATIONS AMERICA, LLC - CA 7,000 (9.33%)

TON80 COMMUNICATIONS, LLC 7,000 (9.33%)

BARR TELL USA, LLC 3,000 (4.00%)

U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 2,000 (2.67%)

HD CARRIER LLC 1,000 (1.33%)

WAVENATION, LLC 1,000 (1.33%)

Cities and Towns in Area Code 820

Arroyo Grande, California Atascadero, California Bakersfield, California Bradley, California Camarillo, California Cambria, California Carpinteria, California Carr, California Cayucos, California Conejo, California El Rio, California Fillmore, California Gaviota, California Guadalupe, California Lompoc, California Los Alamos, California Moorpark, California Morro Bay, California Newbury Park, California Nipomo, California Oak View, California Ojai, California Oxnard, California Parkfield, California Paso Robles, California Piru, California Pismo Beach, California Point Mugu Nawc, California San Luis Obispo, California San Miguel, California Santa Barbara, California Santa Margarita, California Santa Maria, California Santa Paula, California Santa Ynez, California Saticoy, California Simi Valley, California Somis, California Thousand Oaks, California Ventura, California

These geographic regions are also served by area code 805.

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 820, 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