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ZIP stands for Zone Improvement Plan. The codes went live on July 1, 1963.The lowest ZIP code is 00501 — the IRS in Holtsville, New York.The highest ZIP code is 99950, in Ketchikan, Alaska.Type 07734 into a calculator and turn it upside down: hELLO. It is Keansburg, New Jersey.12345 belongs to one company: General Electric in Schenectady, New York.The first digit is a region: 0 is New England and New Jersey, 9 is the West Coast, Alaska and Hawaii.Mr. ZIP, the cartoon mailman, was the mascot that sold the idea to America.ZIP+4 arrived in 1983 and can narrow a ZIP down to one side of one block.A ZIP code is a mail route, not a place: plenty of them cross county and even state lines.Play ZIP Hunt: guess the secret ZIP code of the day in six tries.
zipcodes.pro — AREA-CODE/820

820 area code

Area code 820 is in California. It covers Oxnard, Simi Valley, Thousand Oaks and 68 other places: 106 ZIP codes in Ventura, Santa Barbara, San Luis Obispo and 1 other county. Local time there is , Pacific Time. In service since 2018 as an overlay: it covers the same area as 805, so a number from there can have either code.

Time zone
Pacific
Largest city
Oxnard
Overlays
805
In service since
2018
Rate centres
31
Prefixes assigned
98 (980,000 numbers)

Who calls from a 820 number

NANPA records the carrier each block of 820 numbers is assigned to. Of the 864,000 820 numbers assigned, 54% are with cable, internet-calling, business and other carriers (Onvoy, Fractel and Commio); 46% with mobile carriers (AT&T Mobility, T-Mobile and Verizon Wireless).

That is who the numbers were assigned to: people keep their number when they change carrier, so any one number may have moved since.

Carriers holding the most 820 numbers
CarrierKindShare
OnvoyCable, VoIP, other33%
AT&T MobilityMobile26%
T-MobileMobile13%
Verizon WirelessMobile7%
FractelCable, VoIP, other5%
CommioCable, VoIP, other3%

An area code says where a number was issued, not where the caller is: people keep their numbers when they move, and caller ID can be set to show any number, which the FCC calls spoofing. If a call you did not expect asks for money or personal details, the FCC advises hanging up and calling the company back on a number you look up yourself. Unwanted calls can be reported to the FTC at ReportFraud.ftc.gov.

Places in area code 820

The 27 places with a telephone rate centre of their own using 820, largest first. Each links to its ZIP codes.

Places in area code 820
PlaceZIP codesPopulation
Oxnard, CA 7 200,928
Simi Valley, CA 5 125,634
Thousand Oaks, CA 3 125,205
Santa Maria, CA 5 110,462
Ventura, CA 8 109,857
Santa Barbara, CA 17 87,779
Camarillo, CA 3 70,186
San Luis Obispo, CA 8 48,491
Lompoc, CA 3 43,646
Newbury Park, CA 2 43,472
Paso Robles, CA 2 31,446
Santa Paula, CA 2 31,376
Atascadero, CA 2 29,712
Arroyo Grande, CA 2 18,372
Nipomo, CA 1 17,516
Fillmore, CA 2 16,816
Guadalupe, CA 1 8,566
Pismo Beach, CA 2 8,014
Ojai, CA 2 7,577
El Rio, CA — 6,368
Oak View, CA 1 6,141
Santa Ynez, CA 1 4,467
Cayucos, CA 1 2,427
Piru, CA 1 2,185
Los Alamos, CA 1 1,163
Bradley, CA 1 112
Point Mugu Nawc, CA 1 99

Nearby places using 820

These places have no rate centre of their own in NANPA's records; the nearest one uses 820. Near an area-code boundary that can be wrong for part of a town.

ZIP codes in area code 820

106 ZIP codes in 41 towns, by the town each is mailed to, largest first. Each links to its own page.

Where 820 numbers are issued

NANPA's rate centres with the most 820 prefixes (each prefix is 10,000 numbers), under NANPA's own abbreviated names.

Rate centres using area code 820
Rate centrePlacePrefixes
CAMARILLO Camarillo 12
NEWBURYPRK Newbury Park 10
ATASCADERO Atascadero 8
OXNARD Oxnard 8
SANBARBARA Santa Barbara 8
SANTAMARIA Santa Maria 6

Counties

The counties of its ZIP codes, most residents first, with how many of its ZIP codes each has.

Which code covers where you are now? What area code am I in? answers from your location.

Questions about area code 820

Where is area code 820?

Area code 820 is in California. It covers Oxnard, Simi Valley, Thousand Oaks and 68 other places: 106 ZIP codes in Ventura, Santa Barbara, San Luis Obispo and 1 other county.

What ZIP codes are in area code 820?

106 ZIP codes, by the town each is mailed to: Oxnard (7, 93030 to 93036), Simi Valley (5, 93062 to 93099), Thousand Oaks (3, 91358 to 91362), Santa Maria (5, 93454 to 93458) and 37 more towns. The full list is on this page.

What time zone is area code 820 in?

Pacific time.

Is a 820 number a mobile or a landline?

It can be either. 46% of 820 numbers are assigned to mobile carriers and 0% to local phone companies (NANPA, 2026-10-10); the rest are with cable, internet-calling, business and paging carriers. A number keeps its area code when it moves to another carrier.

What area codes overlay 820?

805. They cover the same area as 820, so a new number there can be given any of them.

Does a 820 number mean the caller is in California?

Not necessarily. An area code says where the number was first issued. People keep their numbers when they move or switch carriers, and calling software can show any number, so a 820 call can come from anywhere.

Other area codes in California

All 41 California area codes, by area, with the cities each covers

Source: NANPA NPA database, central office code and thousands-block assignments, 2026-10-10. Places are matched to NANPA's rate centres by name; see sources.

Cite this page

zipcodes.pro. “Area code 820.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/area-code/820

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