Area code
840
840 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 840
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 840 at a glance
NANPA lists 124 central office codes (prefixes) in use in area code 840, held by 14 holders across 19 rate centers.
| Fact | Value |
|---|---|
| In service since | 2021-02-23 |
| Time zone | Pacific (P) |
| Assigned overlays | 909 (1992-11-14) |
| Prefixes in use | 124 |
| Pooled prefixes | 124 (100%) |
| Rate centers | 19 |
| Companies holding prefixes | 14 |
| Assignment dates on file | 2020-12-23 to 2026-08-11 (124 prefixes) |
| ZIP codes in its places | 31 |
Rate centers in area code 840
| Rate center | Prefixes | Share |
|---|---|---|
| POMONA | 16 | 13% |
| ARROWHEAD | 14 | 11% |
| FONTANA | 12 | 10% |
| S BERNDINO | 12 | 10% |
| CHINO | 8 | 6% |
| CLAREMONT | 8 | 6% |
| ONTARIO | 7 | 6% |
| UPLAND | 7 | 6% |
| 11 other rate centers | 40 | 32% |
Who holds the prefixes in 840
T-Mobile USA holds the most prefixes, 32 (26%). 100% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
| Holder | Prefixes | Share |
|---|---|---|
| T-Mobile USA | 32 | 26% |
| Fractel | 26 | 21% |
| Onvoy | 21 | 17% |
| New Cingular Wireless PCS | 16 | 13% |
| Verizon Wireless | 12 | 10% |
| Bandwidth.com CLEC | 4 | 3% |
| 8 other carriers | 13 | 10% |
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 840
- 1992-11-14 Area code 909, named as the parent of 840 in the NANPA report, was in service.
- 2021-02-23 Area code 840 went into service.
Area codes nearest to 840
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 840
31 ZIP codes fall in places that have a rate center in this area code.
| Place | ZIP codes |
|---|---|
| Fontana, CA | 5 |
| Ontario, CA | 4 |
| Pomona, CA | 4 |
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 840 numbers
97 FCC complaints are on file for 94 numbers in 840, most often filed as "Unwanted Calls". These are unverified consumer reports.
| Year of latest complaint | Numbers |
|---|---|
| 2023 | 17 |
| 2024 | 17 |
| 2025 | 9 |
Other area codes in California
California is one state with 41 area codes in the NANPA table. 840 is one of them.
- 209
- 213
- 279
- 310
- 323
- 341
- 350
- 357
- 369
- 408
- 415
- 424
- 442
- 510
- 530
- 559
- 562
- 619
- 626
- 628
- 650
- 657
- 661
- 669
- 707
- 714
- 738
- 747
- 760
- 805
- 818
- 820
- 831
- 837
- 858
- 909
- 916
- 925
- 949
- 951
Next to 840 in the numbering table
These are the codes just before and after 840 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 840 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 840 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 840
Where is area code 840?
NANPA assigns area code 840 to California, United States.
In which state does area code 840 sit?
California. 840 is one of 41 area codes the NANPA table assigns to the state.
Which places does area code 840 cover?
The places with the most ZIP codes among the rate centers in 840 are Fontana, CA, Ontario, CA and Pomona, CA. The rate center list on this page shows all of them.
Who owns area code 840?
NANPA assigns area codes. Within 840, T-Mobile USA holds the most prefixes, 32 prefixes or 26%.
Which time zone does 840 use?
The NANPA NPA report lists the time zone for 840 as Pacific (P).
What year did 840 enter service?
The NANPA NPA report gives an in-service date of 2021-02-23, so 840 has been in use since 2021.
Does area code 840 have an overlay?
Yes. 909 (in service 1992-11-14) shares the same area with 840, so numbers from all of them are local to each other.
Which area codes are nearest to 840?
The area codes closest to 840, measured between the centers of the ZIP code places they serve, are 626 (about 21 miles), 657 (about 29 miles), 714 (about 29 miles), 951 (about 33 miles) and 562 (about 36 miles).
How many prefixes does area code 840 have?
NANPA's report dated 2026-10-17 lists 124 prefixes in service in 840, spread over 19 rate centers and 14 holders.
Are there complaints about 840 numbers?
The FCC data on file has 97 complaints for 94 numbers in 840. 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.