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Before You Call Back

Area code 831

Area code 831 serves California, including Salinas, Santa Cruz and Monterey (Pacific time). It has been in service since July 11, 1998.

Numbers starting with 831 drew 1,010 reports to the FTC from Aug 14, 2026 to Nov 11, 2026 and 261 complaints to the FCC since November 2023. The number on your screen can be faked, so an 831 number proves nothing about where a call came from.

Location
CaliforniaSan Francisco-Oakland-Fremont, CA Metropolitan Statistical Area and San Jose-Sunnyvale-Santa Clara, CA Metropolitan Statistical Area
Time zone
Pacific
In service since
July 11, 1998Created from 408
Overlay
None: the only code for its area
Local calls
Dial 7 digits
Exchanges in use
406 of 792held by 45 carriers
Projected to run out
4Q 2080NANPA forecast 2026.2

Complaints about 831 numbers

Reports where the number on the consumer's caller ID (or, for the FCC, the number the caller asked them to call back) starts with 831. These are counts of what people reported; the agencies do not verify them.

FTC reports, Aug 14, 2026 to Nov 11, 2026

1,010

FCC complaints since November 2023

261

Different 831 numbers reported

1,194

FCC complaints naming an 831 number, by month

November 2023 to October 2026. Source: FCC Consumer Complaints Data.

Show as a table
MonthComplaints
November 202315
December 20238
January 20244
February 20245
March 20244
April 20245
May 202414
June 20247
July 20247
August 20248
September 20245
October 20247
November 20247
December 20245
January 20256
February 20258
March 20257
April 20259
May 20256
June 20255
July 20256
August 20259
September 20258
October 20250
November 20251
December 20256
January 20266
February 202611
March 20266
April 20266
May 202610
June 20266
July 202610
August 20268
September 202612
October 202610

What people said 831 calls were about

Subjects picked in FTC reports, August 14, 2026 to November 11, 2026. 726 of 1,010 reports were robocalls.

Show as a table
SubjectReports
Reducing your debt (credit cards, mortgage, student loans)399
Other323
Calls pretending to be government, businesses, or family and friends108
Dropped call or no message78
Medical and prescriptions9
Energy, solar, and utilities6

Most reported 831 numbers

Numbers with at least five reports from three or more places in the last twelve months. Many of them are likely spoofed.

Places served by 831

NANPA lists 24 rate centers for 831. A rate center is the town or district a block of numbers is tied to for billing; sorted here by how many exchanges each holds.
  • Salinas84
  • Santa Cruz76
  • Monterey64
  • Watsonville30
  • Hollister22
  • Aptos19
  • Carmel12
  • Ben Lomond11
  • Boulder Creek9
  • Felton9
  • Soledad8
  • Gonzales7
  • Greenfield (monterey)7
  • King City7
  • Big Sur6
  • Castroville6
  • Tres Pinos6
  • Carmel Valley5
  • Chualar4
  • San Ardo4
  • San Juan4
  • San Lucas4
  • Idria1
  • Pinnacles1

Phone companies holding 831 exchanges

Each exchange (the three digits after the area code) is assigned to one carrier. 76% of these exchanges are pooled: their numbers are handed out in blocks of 1,000 to other carriers, so the holder below is not always the company serving a given number.

Exchanges held, top 8 of 45 carriers

NANPA central office code assignments, file of November 11, 2026.

Show as a table
Carrier (legal name)Exchanges
Pacific Bell124
New Cingular Wireless PCS, LLC35
Onvoy, LLC - CA31
Cellco Partnership dba Verizon Wireless - CA30
Level 3 Communications, LLC - CA26
IP Horizon LLC14
Metropcs, Inc.13
T-Mobile USA, Inc.13

When today's 831 exchanges were assigned

Exchanges still assigned, by year of assignment. Exchanges returned since are not counted.

Show as a table
YearExchanges
200113
20025
20031
20055
20063
20071
20084
20095
20101
20111
20143
20156
201610
20173
20183
20196
20207
20216
202211
20238
20249
20254
20265

Check an 831 number

A check shows the carrier and rate center of the number's exchange and every FTC and FCC report about that exact number. Why the number on screen can be fake.

Other area codes in California

NANPA area code database and central office code file of November 11, 2026; FCC complaints November 1, 2023 to November 11, 2026; FTC reports August 14, 2026 to November 11, 2026. How the data is used.

Official sources (7)Show