Area code
510
510 is a United States area code. Under the North American Numbering Plan it belongs to California, which has 41 area codes in total.
Validate a number in 510
Paste a full number and the tool checks it against the numbering plan. It returns the standard formats, the line type the plan assigns and the area code region.
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Area code 510 at a glance
NANPA lists 785 central office codes (prefixes) in use in area code 510, held by 31 holders across 13 rate centers.
| Fact | Value |
|---|---|
| In service since | 1991-09-02 |
| Time zone | Pacific (P) |
| Assigned overlays | 341 (2019-07-22) |
| Prefixes in use | 785 |
| Pooled prefixes | 514 (65%) |
| Rate centers | 13 |
| Companies holding prefixes | 31 |
| Assignment dates on file | 2001-01-25 to 2026-02-25 (191 prefixes) |
| ZIP codes in its places | 15 |
Rate centers in area code 510
| Rate center | Prefixes | Share |
|---|---|---|
| OKLD MN-PD | 204 | 26% |
| HAYWARD | 117 | 15% |
| FRNK MAIN | 81 | 10% |
| OKLD BKLY | 70 | 9% |
| OKLD TRNID | 60 | 8% |
| RICHMOND | 53 | 7% |
| FRNK OLIVR | 45 | 6% |
| OKLD ALMD | 42 | 5% |
| 5 other rate centers | 113 | 14% |
Who holds the prefixes in 510
Pacific Bell holds the most prefixes, 277 (35%). 65% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
| Holder | Prefixes | Share |
|---|---|---|
| Pacific Bell | 277 | 35% |
| New Cingular Wireless PCS | 78 | 10% |
| T-Mobile USA | 65 | 8% |
| Verizon Wireless | 60 | 8% |
| Mcimetro Access Transmission Services | 48 | 6% |
| Metropcs | 45 | 6% |
| 25 other carriers | 212 | 27% |
A prefix holder is the company a code was assigned to, not necessarily a number's current carrier, because numbers can be ported to another company. Find which carrier a number is on, or browse the prefix holders.
History of area code 510
- 1947-01-01 Area code 415, named as the parent of 510 in the NANPA report, was in service.
- 1991-09-02 Area code 510 went into service.
- 1998-03-14 Area code 925 went into service and names 510 as its parent.
- 2019-07-22 Area code 341 went into service as an overlay in the same area as 510.
Area codes nearest to 510
Distance is measured between the centers of the ZIP code places each area code serves, so it is a rough guide.
Overlay codes in the same area
ZIP codes in area code 510
15 ZIP codes fall in places that have a rate center in this area code.
| Place | ZIP codes |
|---|---|
| Hayward, CA | 7 |
| Richmond, CA | 7 |
| Crockett, CA | 1 |
A ZIP code and an area code are unrelated systems. A ZIP code can sit in more than one area code, and an area code spans many ZIP codes.
Complaints on file for 510 numbers
4,286 FCC complaints are on file for 2,800 numbers in 510, most often filed as "Unwanted Calls". These are unverified consumer reports.
| Year of latest complaint | Numbers |
|---|---|
| 2023 | 142 |
| 2024 | 91 |
| 2025 | 114 |
Other area codes in California
California is one state with 41 area codes in the NANPA table. 510 is one of them.
- 209
- 213
- 279
- 310
- 323
- 341
- 350
- 357
- 369
- 408
- 415
- 424
- 442
- 530
- 559
- 562
- 619
- 626
- 628
- 650
- 657
- 661
- 669
- 707
- 714
- 738
- 747
- 760
- 805
- 818
- 820
- 831
- 837
- 840
- 858
- 909
- 916
- 925
- 949
- 951
Next to 510 in the numbering table
These are the codes just before and after 510 when all are sorted by number. They are neighbours on the list, not necessarily on the map.
What the area code does and does not tell you
A number that starts with 510 was first assigned in California. That is a fact about where the number began, and it is a useful hint when you check a form entry, for example a billing address in California next to a 510 phone number.
It does not show where the person is today. A number stays with its owner after a move or a change of provider (number portability), and mobile numbers travel with the handset. The area code also cannot tell you whether the line is active, who the carrier is, or whether the number is mobile or fixed: the plan shares those ranges. Read more about the area code, the numbering plan and line type.
Check numbers in bulk with the API
| Product | Credits | Docs |
|---|---|---|
| Phone Numbering-Plan Validation | 1 credit per valid number | API docs |
| Phone Intelligence (carrier and line status) | 1 credit per check (invalid numbers outside the US and Canada are free) | Product page |
Questions about area code 510
Where is area code 510?
NANPA assigns area code 510 to California, United States.
In which state does area code 510 sit?
California. 510 is one of 41 area codes the NANPA table assigns to the state.
Which places does area code 510 cover?
The places with the most ZIP codes among the rate centers in 510 are Hayward, CA, Richmond, CA and Crockett, CA. The rate center list on this page shows all of them.
Who owns area code 510?
NANPA assigns area codes. Within 510, Pacific Bell holds the most prefixes, 277 prefixes or 35%.
Which time zone does 510 use?
The NANPA NPA report lists the time zone for 510 as Pacific (P).
What year did 510 enter service?
The NANPA NPA report gives an in-service date of 1991-09-02, so 510 has been in use since 1991.
Does area code 510 have an overlay?
Yes. 341 (in service 2019-07-22) shares the same area with 510, so numbers from all of them are local to each other.
Which area codes are nearest to 510?
The area codes closest to 510, measured between the centers of the ZIP code places they serve, are 925 (about 13 miles), 415 (about 25 miles), 628 (about 25 miles), 650 (about 25 miles) and 669 (about 43 miles).
How many prefixes does area code 510 have?
NANPA's report dated 2026-10-17 lists 785 prefixes in service in 510, spread over 13 rate centers and 31 holders.
Are there complaints about 510 numbers?
The FCC data on file has 4,286 complaints for 2,800 numbers in 510. They are unverified consumer reports. A number with no complaints on file is not proven safe.
Area code assignments: North American Numbering Plan Administrator NPA report, file dated 10/17/2026, retrieved 2026-10-17. Source file. New codes are assigned several times a year. Prefixes, rate centers, holders, time zone, in-service date and overlays: NANPA central office code report dated 2026-10-17 and NPA report dated 2026-10-18. Complaints: FCC consumer complaints open data, fetched 2026-10-17. ZIP code places: Postal code places and coordinates: GeoNames (geonames.org), licensed CC BY 4.0.