Area code
628
628 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 628
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Area code 628 at a glance
NANPA lists 192 central office codes (prefixes) in use in area code 628, held by 32 holders across 14 rate centers.
| Fact | Value |
|---|---|
| In service since | 2015-03-21 |
| Time zone | Pacific (P) |
| Assigned overlays | 415 (1947-01-01) |
| Prefixes in use | 192 |
| Pooled prefixes | 191 (99%) |
| Rate centers | 14 |
| Companies holding prefixes | 32 |
| Assignment dates on file | 2014-09-29 to 2025-11-06 (177 prefixes) |
| ZIP codes in its places | 16 |
Rate centers in area code 628
| Rate center | Prefixes | Share |
|---|---|---|
| SNFC CNTRL | 76 | 40% |
| SNFC MT-EV | 26 | 14% |
| SAN RAFAEL | 16 | 8% |
| SNFC JUNPR | 14 | 7% |
| BELVEDERE | 10 | 5% |
| CORTEMADRA | 7 | 4% |
| MILLVALLEY | 7 | 4% |
| NOVATO | 7 | 4% |
| 6 other rate centers | 29 | 15% |
Who holds the prefixes in 628
Fractel holds the most prefixes, 33 (17%). 99% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
| Holder | Prefixes | Share |
|---|---|---|
| Fractel | 33 | 17% |
| Onvoy | 31 | 16% |
| T-Mobile USA | 28 | 15% |
| Teleport Communications America | 17 | 9% |
| Bandwidth.com CLEC | 13 | 7% |
| New Cingular Wireless PCS | 12 | 6% |
| 26 other carriers | 58 | 30% |
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 628
- 1947-01-01 Area code 415, named as the parent of 628 in the NANPA report, was in service.
- 2015-03-21 Area code 628 went into service.
Area codes nearest to 628
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 628
16 ZIP codes fall in places that have a rate center in this area code.
| Place | ZIP codes |
|---|---|
| Novato, CA | 5 |
| San Rafael, CA | 5 |
| Mill Valley, CA | 2 |
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 628 numbers
896 FCC complaints are on file for 666 numbers in 628, most often filed as "Unwanted Calls". These are unverified consumer reports.
| Year of latest complaint | Numbers |
|---|---|
| 2023 | 40 |
| 2024 | 55 |
| 2025 | 62 |
Other area codes in California
California is one state with 41 area codes in the NANPA table. 628 is one of them.
- 209
- 213
- 279
- 310
- 323
- 341
- 350
- 357
- 369
- 408
- 415
- 424
- 442
- 510
- 530
- 559
- 562
- 619
- 626
- 650
- 657
- 661
- 669
- 707
- 714
- 738
- 747
- 760
- 805
- 818
- 820
- 831
- 837
- 840
- 858
- 909
- 916
- 925
- 949
- 951
Next to 628 in the numbering table
These are the codes just before and after 628 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 628 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 628 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 628
Where is area code 628?
NANPA assigns area code 628 to California, United States.
In which state does area code 628 sit?
California. 628 is one of 41 area codes the NANPA table assigns to the state.
Which places does area code 628 cover?
The places with the most ZIP codes among the rate centers in 628 are Novato, CA, San Rafael, CA and Mill Valley, CA. The rate center list on this page shows all of them.
Who owns area code 628?
NANPA assigns area codes. Within 628, Fractel holds the most prefixes, 33 prefixes or 17%.
Which time zone does 628 use?
The NANPA NPA report lists the time zone for 628 as Pacific (P).
What year did 628 enter service?
The NANPA NPA report gives an in-service date of 2015-03-21, so 628 has been in use since 2015.
Does area code 628 have an overlay?
Yes. 415 (in service 1947-01-01) shares the same area with 628, so numbers from all of them are local to each other.
Which area codes are nearest to 628?
The area codes closest to 628, measured between the centers of the ZIP code places they serve, are 341 (about 25 miles), 510 (about 25 miles), 925 (about 35 miles), 650 (about 42 miles) and 669 (about 66 miles).
How many prefixes does area code 628 have?
NANPA's report dated 2026-10-17 lists 192 prefixes in service in 628, spread over 14 rate centers and 32 holders.
Are there complaints about 628 numbers?
The FCC data on file has 896 complaints for 666 numbers in 628. 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.