---
title: "Area code 628: California, United States"
url: "https://lookvalid.com/area-code/628.md"
canonical_url: "https://lookvalid.com/area-code/628"
last_updated: "2026-10-23"
type: "reference"
summary: "Area code 628 serves California, United States. Number formats, numbering rules, a live phone validator and the other codes in California."
---

# Area code 628: California, United States

Area code 628 serves California, United States. Number formats, numbering rules, a live phone validator and the other codes in California.

NANPA lists 192 central office codes (prefixes) in use in area code 628, held by 32 holders across 14 rate centers.
Fractel holds the most prefixes, 33 (17%). 99% of the prefixes are pooled, which means their thousands-blocks can belong to different companies.
The FCC unwanted-call data has 896 complaints on file for 666 numbers in 628, most often filed as "Unwanted Calls". These are consumer reports, not findings.

## Facts

- 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

| 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% |

## Carriers

| 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.

## History

- 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.

## Nearest area codes

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).

## ZIP codes

16 ZIP codes fall in places that have a rate center in this area code. The places with the most are Novato, CA (5 ZIP codes), San Rafael, CA (5 ZIP codes) and Mill Valley, CA (2 ZIP codes). A ZIP code and an area code are unrelated systems, so a ZIP code can sit in more than one area code and an area code spans many ZIP codes.

## Complaints on file

896 complaints for 666 numbers. Numbers whose latest complaint falls in each year:

- 2023: 40
- 2024: 55
- 2025: 62

## Questions

### 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.

Sources: NANPA central office code report dated 2026-10-17; NANPA NPA report dated 2026-10-18; FCC unwanted-call complaints, data fetched 2026-10-17; ZIP code places from GeoNames (CC BY 4.0).