628 area code — San Francisco and Marin County, CA (overlay of 415)
The overlay San Francisco approved in 1999 and shelved the same year, then brought back in 2013 once number conservation had run its course. In service since March 21, 2015 over exactly the same ground as 415, it now holds most of the city’s spare numbers.
New numbers available in 628Area code 628 covers the City and County of San Francisco, most of Marin County and a corner of San Mateo County — the same area as 415, street for street. It was laid over 415 on March 21, 2015 because 415 was about to run out of prefixes.
Nobody’s number changed. New lines can be issued from either code, and with 786 of 415’s 792 possible prefixes already assigned against 193 in 628, most of the room for new San Francisco numbers is in 628. Every call is dialled with 1 plus ten digits.
Area code 628 at a glance
- State
- California
- County
- San Francisco, most of Marin, and a corner of San Mateo
- Region
- San Francisco and Marin County
- Time zone
- Pacific Time (PT)
- In service since
- March 21, 2015
- Type
- Overlay code
How a 628 number is built
Every North American number has four parts. Knowing where the seams fall answers most of what people ask about 628.
The code and the exchange together are the NPA-NXX: what each group of digits means.
Cities and areas served by 628
- San Francisco
- San Rafael
- Novato
- Mill Valley
- Sausalito
- Corte Madera
- Larkspur
Codes sharing the same area
One other code covers the same ground as 628.
Nearby area codes
Bordering California and the surrounding region. A number in one of these is close to 628 but not in it.
How 628 came about
Approved, shelved, and approved again fourteen years later.
- December 1998NANPA asks for a new codeWith new telephone companies entering the market, the supply of 415 prefixes is low enough that NANPA petitions the CPUC for relief.
- April 1, 1999628 is approved as an overlayIn Decision 99-04-025 the CPUC approves 628 as an overlay of 415, to go into service on October 21, 2000.
- December 16, 1999Every overlay is suspendedResponding to public opposition to the spread of new codes, the commission indefinitely suspends the overlays it had approved, 628 among them, in Decision 99-12-051. Thousand-block number pooling and other conservation measures stretch 415 for years.
- September 6, 2012The industry agrees on an overlayNANPA meets the carriers serving 415; the consensus is to recommend an overlay. The CPUC holds four public meetings in January 2013.
- December 19, 2013Approved againWith 415 forecast to exhaust in the third quarter of 2015, the CPUC approves the all-services overlay in Decision 13-12-055. A split is ruled out because about 65% of 415’s numbers are in one rate centre.
- February 21, 2015Ten-digit diallingDialling 1 plus the area code becomes mandatory for every call from a 415 phone, a month before any 628 number exists, so that the two codes can share the area.
- March 21, 2015628 goes into serviceThe first 628 numbers can be issued. They share the same local calling area as 415 numbers, and the price of a call does not change.
Which code should you choose?
628 and 415 are interchangeable in San Francisco and Marin. The codes around the bay are not.
| Code | Covers | What it means |
|---|---|---|
| 628 | San Francisco and Marin since March 21, 2015 | Newest, with 599 of its 792 possible prefixes not yet assigned |
| 415 | The same area since 1947 | The original; six of its possible prefixes remain unassigned |
| 650 | San Mateo County and the Peninsula | South of the city line since 1997 |
| 510 and 341 | Oakland and the East Bay | Across the bay |
| 408 and 669 | San Jose and the South Bay | The far end of the bay |
| 707 | The North Coast beyond Marin | North of the 415/628 area |
To anyone in San Francisco a 628 number is as local as a 415 one. The difference is age and supply: 415 is the code people know, 628 is the code with room.
628 by the numbers
Counted from prefix assignment records on October 19, 2026. Each prefix holds up to 10,000 numbers. Every one of the area’s fourteen rate centres now has 628 prefixes; the shares show where ten years of demand have gone.
| Rate centre | 628 prefixes | Share of all 628 |
|---|---|---|
| San Francisco (three rate centres) | 116 | 60% |
| San Rafael | 17 | 9% |
| West Marin: Point Reyes, Stinson Beach–Bolinas, Nicasio, Inverness | 16 | 8% |
| Novato and Ignacio | 13 | 7% |
| Belvedere | 10 | 5% |
| Sausalito | 7 | 4% |
| Mill Valley | 7 | 4% |
| Corte Madera | 7 | 4% |
| Total prefixes | 193 | 100% |
Ten years in, 628 has a quarter as many prefixes as 415, with the same shape: six in ten are in San Francisco itself. Belvedere is the one place where 628 is close to catching up, with 10 prefixes to 415’s 15.
What people get wrong about 628
Is 628 used for spam calls?
Because 628 is younger than 415 and less familiar, a 628 number on the screen makes some people suspicious and others trusting, and scammers use both reactions. The code itself proves nothing: caller ID is set by the calling system, and a San Francisco number can be dialled from anywhere. Carriers attach STIR/SHAKEN attestation to calls, which flags much spoofing, but the test is the request, not the digits. A call that wants payment, a passcode or personal details should be ended and the organisation rung back on a number you already have.
Sources
- NANPA area code report: 628 (npa_report.csv, file dated October 19, 2026: 628 assigned 19-Dec-2013, in service 21-Mar-2015, parent 415, overlay complex 415/628; 1+10-digit local dialling)
- CPUC press release, December 19, 2013: CPUC approves new 628 area code overlay to 415 area code (all-services overlay approved; exhaust expected by October 2015; the September 6, 2012 industry meeting and the January 2013 public meetings; the December 1998 petition)
- CPUC Decision 13-12-055, Application 13-05-013 (the April 1, 1999 approval in D.99-04-025 and the December 16, 1999 suspension in D.99-12-051; thousand-block pooling; 14 rate centres; about 65% of numbers in San Francisco Central; exhaust in the third quarter of 2015; permissive dialling through February 2015)
- CPUC release, January 22, 2015: San Francisco and parts of Marin County to dial calls differently (mandatory 1 + area code + number from February 21, 2015; 628 numbers issued from March 21, 2015 with the same local calling area; prices unchanged; 911 unaffected)
- CPUC report on the 415 area code, November 28, 2000 (the overlay scheduled for October 21, 2000; suspended in response to public opposition to new area codes)
- NANPA 2026-1 NPA exhaust projections, April 2026 (415/628 projected to exhaust in 4Q 2072, from 1Q 2065 in the October 2025 forecast)
- Prefix assignment records for 415 and 628 (read October 19, 2026: 193 prefixes assigned in 628 and 786 in 415, across fourteen rate centres)
Area code 628 FAQ
Where is area code 628?
Area code 628 is San Francisco, California, and most of Marin County, the same area as 415. It reaches a corner of San Mateo County at Brisbane and part of Daly City.
Is 628 a San Francisco area code?
Yes. 628 was laid over 415 on March 21, 2015 and covers exactly the same ground: the City and County of San Francisco and most of Marin County.
Is 628 a legitimate area code?
Yes. 628 is a geographic code assigned by NANPA and has been issued in San Francisco and Marin since March 21, 2015. A 628 number is as local as a 415 one.
What is the difference between 415 and 628?
Only age and supply. 415 dates from 1947 and has 786 of its 792 possible prefixes assigned; 628 dates from 2015 and has 193. Both cover the same area and are dialled the same way.
When did the 628 area code start?
Numbers could be issued from March 21, 2015. The code had first been approved as 415’s overlay on April 1, 1999, then suspended on December 16, 1999, before being approved again on December 19, 2013.
Can I get a 415 number instead of a 628 one?
Sometimes. Carriers can still issue a 415 number from blocks they hold, but with six of 415’s possible prefixes unassigned against 599 in 628, most of the supply is 628. The two work identically.
What time zone is the 628 area code in?
Pacific Time: UTC−8 in winter and UTC−7 in summer.
Do I dial 1 before a 628 number?
From a phone in the 415/628 area, yes: since February 21, 2015 every call is dialled 1 + area code + number. From elsewhere in the United States, dial it like any other ten-digit number.
Is Marin County in the 628 area code?
Yes. Eleven of the area’s fourteen rate centres are in Marin County: San Rafael, Novato, Mill Valley, Sausalito, Belvedere, Corte Madera and the towns of West Marin all have 628 as well as 415 prefixes.
Will San Francisco need another area code?
Not for decades on current forecasts. NANPA’s April 2026 projection puts 415 and 628 together at exhaust in the fourth quarter of 2072.
Getting a 628 business number
628 numbers are still being issued, so a business anywhere can hold one and route it to wherever its team actually works — you do not need an address in California.
- STIR/SHAKENAttested, so calls are less likely to show as spam
- AI receptionistCover for the hours nobody is at a desk
- Free portingIf you already hold a 628 number
- Recording & SMSOn the same line, no add-on