Area code 831

At a glance

Country code

+1

State

CA

Exchanges on record

442

Carriers on record

37

Most exchanges: AT&T 176, Verizon 41, Onvoy 31.

The exchange map

Formats and patterns

Any 831 number, in E.164

^\+1831[2-9]\d{6}$

+1, the area code, a central office code that does not start with 0 or 1, then four digits.

^\+1831(?:2(?:0[16-8]|1[024]|2[479]|3[14-689]|4[035-7]|5[12468]|6[0-26]|7[7-9]|8[14]|9[12457])|3(?:14|2[015-7]|3[0-249]|4[056]|83)|4(?:0[26]|19|28)|5(?:[04]0|12|2[14]|3[79]|66|78|8[58]|9[4-6])|6(?:01|73|82)|7(?:1[03]|[49]4|[56]0|7[46]|85)|8(?:0[189]|18|21|40|69)|9(?:0[25]|1[57]|31|70))\d{4}$

^\+1831(?:2(?:0[235]|1[6-9]|2[238]|33|4[12]|5[359]|6[79]|7[04]|8[89]|9[0369])|3(?:0[025-7]|1[23679]|24|3[35-8]|5[09]|7[235]|8[24-69]|9[2-4])|4(?:01|2[0-79]|3[01589]|4[02-49]|5[457-9]|6[0-24-69]|7[15-79]|84)|5(?:02|[12]5|3[13-6]|7[245]|8[23]|93)|6(?:00|12|2[0-8]|3[02-8]|4[1-9]|5[25-9]|6[1-57]|7[4-9]|8[457-9]|93)|7(?:0[35-79]|18|2[2468]|3[27]|4[01]|5[13-9]|6[13689]|7[0-258]|8[3469]|96)|8(?:[25]4|8[13469]|99)|9(?:01|2[01]|[49]8|75))\d{4}$

^\+1831(?:2(?:0[04]|15|2[0156]|3[027]|4[49]|5[07]|6[3-58]|7[1-356]|8[0235-7]|98)|3(?:0[13489]|1[58]|2[289]|4[38]|5[36]|6[56]|8[78])|4(?:[08]0|17|32|53|[69]8)|5(?:08|29|32|76|8[067]|97)|6(?:0[3479]|1[038]|53|66|99)|7(?:0[48]|[147]7|31|88)|8(?:00|3[037]|4[24]|5[01569]|[67]7|8[078])|9(?:00|46|9[69]))\d{4}$

The exchange patterns follow the original allocations; a number ported since keeps its digits but not necessarily its carrier or its line type.

Carriers and their exchanges

Every carrier holding exchanges in 831, with the exchanges allocated to it (the three digits after the area code).

Questions developers ask

Where is area code 831?

Area code 831 is in California, in the United States: all 442 of its exchanges on record are there. From abroad it is dialled +1 831, then the seven-digit number.

Is a 831 number mobile or landline?

Either: in the North American Numbering Plan the line type belongs to the exchange (the three digits after the area code), not to the area code. Of the 442 exchanges on record in 831, 98 (22%) were allocated as mobile, 210 (48%) as fixed line, 100 (23%) as VoIP and 34 (8%) have no line type on record. A number can have been ported since, to another carrier and even to another line type.

Which carriers have numbers in area code 831?

37 carriers hold exchanges in 831 on record; the most: AT&T (176), Verizon (41) and Onvoy (31). These are the original allocations: with number portability, a number may be served by another carrier today, which only a live carrier lookup (an HLR or MNP query) can tell.

How do I validate a 831 phone number?

In E.164 a 831 number matches ^\+1831[2-9]\d{6}$: +1, the area code, a central office code that does not start with 0 or 1, then four digits. Written nationally it reads (831) 555-0123. The exchange patterns on this page narrow it to the exchanges allocated as mobile, fixed line or VoIP.