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831 Area Code

Area Code Overview

Area code 831 is a geographic telephone area code in California that went into service on July 11, 1998. The geographic regions covered by this area code overlay has a population of approximately 804,270.

Overlay and Dialing Rules

  • Area Code: 831
  • State: California
  • Type: General Purpose Code
  • In Service Date: July 11, 1998
  • Overlay Complex: 831
  • Local Dialing Plan: This area does not require you to dial the area code when calling locally.

Estimated Number of Assigned Phone Numbers in Area Code 831

This area code is ranked 258th out of 363 nationwide in estimated assigned phone numbers. Within the state territory it serves, it is ranked 29th out of 39.

3,070,000

Estimated Service-Type Mix of Assigned Phone Numbers in Area Code 831

Total assigned 3,070,000
Wireless
1,087,000 assigned
35.41%
Wireline and VoIP
1,831,000 assigned
59.64%
Other / Unclassified
152,000 assigned
4.95%

Estimated Share of Wireless Numbers Originally Assigned to Each Carrier in Area Code 831

Estimated assigned wireless phone numbers: 1,087,000

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

AT&T Wireless 382,000 (35.14%)
Verizon Wireless 379,000 (34.87%)
T-Mobile 325,000 (29.90%)
Optimum Mobile 1,000 (0.09%)

Estimated Share of Wireline and VoIP Numbers Originally Assigned to Each Carrier in Area Code 831

Estimated assigned wireline and VoIP phone numbers: 1,831,000

AT&T 651,000 (35.55%)
Onvoy 495,000 (27.03%)
Bandwidth 169,000 (9.23%)
Lumen 98,000 (5.35%)
Spectrum 85,000 (4.64%)
Peerless Network 70,000 (3.82%)
Comcast Business 57,000 (3.11%)
UTILITY TELECOM GROUP, LLC - CA 40,000 (2.18%)
Telnyx 37,000 (2.02%)
TERRA NOVA TELECOM INC. 35,000 (1.91%)
MCIMETRO ACCESS TRANSMISSION SERVICES LLC 28,000 (1.53%)
Commio 26,000 (1.42%)

Other / Unclassified Assigned Numbering in Area Code 831

Estimated assigned other or unclassified phone numbers: 152,000

IP HORIZON LLC 28,000 (18.42%)
TELEPORT COMMUNICATIONS AMERICA, LLC - CA 23,000 (15.13%)
U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 22,000 (14.47%)
PINNACLES TEL. CO. 20,000 (13.16%)
FRACTEL, LLC 15,000 (9.87%)
HD CARRIER LLC 10,000 (6.58%)
NORTH COUNTY COMMUNICATION CORPORATION - CA 10,000 (6.58%)
SHELCOMM 10,000 (6.58%)
TON80 COMMUNICATIONS, LLC 7,000 (4.61%)
WHITESKY COMMUNICATIONS, LLC 4,000 (2.63%)
AIRESPRING, INC. 1,000 (0.66%)
EXIANT COMMUNICATIONS LLC 1,000 (0.66%)

Cities and Towns in Area Code 831

Aptos, California Ben Lomond, California Big Sur, California Boulder Creek, California Carmel, California Carmel Valley, California Castroville, California Chualar, California Felton, California Gonzales, California Greenfield, California Hollister, California Idria, California King City, California Monterey, California Pinnacles, California Salinas, California San Ardo, California San Juan Capistrano, California San Lucas, California Santa Cruz, California Soledad, California Tres Pinos, California Watsonville, California

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 831, 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