The 925 area code covers Walnut Creek, Concord and 12 more places in California.
Area code 925 is in California, on Pacific Time. In the 925 area, phone numbers are given out most in Contra Costa County, then Alameda County. It has been in service since March 14, 1998.
- Where
- Contra Costa County and Alameda County, California
- Time zone
- Pacific Time
- In service since
- March 14, 1998
- Shares its area with
- No other area code
- Prefixes in use
- 640
- How to dial
- Local calls need 1, then the area code, then the number: 1-925-555-0142.
Find out who called you from a 925 number.
Enter the full 10-digit number to see who it is listed to and the city and state on the listing. It is the same free check as our who called me lookup. To see only the caller ID name on the number, use our free CNAM lookup. To see whether it is a mobile, a landline or a VoIP line, use our free VoIP checker. To see which carrier a (925) number is on today, use our free carrier lookup.
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Walnut Creek holds 16% of the phone prefixes in area code 925.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 640 prefixes in use shows where 925 numbers are actually given out.
- Walnut Creek103 prefixes, 16%
- Concord89 prefixes, 14%
- Pleasanton76 prefixes, 12%
- Antioch67 prefixes, 10%
- Livermore50 prefixes, 8%
- Dublin42 prefixes, 7%
- Danville38 prefixes, 6%
- Martinez22 prefixes, 3%
Also served: Pittsburg, Lafayette, Orinda and Clayton and 2 smaller places.
Pacific Bell (AT&T) holds the most phone number prefixes in area code 925: 206 of 640.
NANPA, which runs the North American numbering plan, assigns each prefix (the three digits after the area code) to one carrier. Here is how the 640 prefixes in use in 925 divide between carriers; holders this page does not name are grouped as other carriers.
| Carrier | Prefixes | Share |
|---|---|---|
| Pacific Bell (AT&T)AT&T's landline company | 206 | 32% |
| AT&T MobilityMobile network | 48 | 8% |
| Level 3 (Lumen)Lumen's business and wholesale network | 46 | 7% |
| T-MobileMobile network | 44 | 7% |
| TPX Communications | 37 | 6% |
| Teleport (AT&T)AT&T's business phone network | 25 | 4% |
| 23 other carriers | 234 | 37% |
70% of these prefixes are pooled, which means the blocks of 1,000 numbers inside them can belong to other carriers. Any number can also have been moved to another carrier since, so this shows who holds the prefixes, not who serves a given number.
Want the carrier of one exact number? Our free carrier lookup checks it, because numbers move between carriers.
Source: NANPA central office code assignments, October 1, 2026.
925 has covered the same ground since 1998.
1998
925 starts on March 14, 1998, split off from 510.
A 925 number on your screen can still be a scam, because caller ID is easy to fake.
- Let an unknown call go to voicemail. A real caller leaves a message; a robocaller usually does not.
- Look the number up with the box above before you call back, because calling back tells a robocaller your line is live.
- Hang up on anyone who wants gift cards, crypto or a wire transfer, or asks you to read out a code that was just texted to you.
- Report unwanted robocalls at reportfraud.ftc.gov, or paste a suspicious message into our free scam checker.
The area codes closest to 925 are 510, 650 and 408.
This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.
California has 40 other area codes.
These are the questions people ask most about area code 925.
Where is area code 925?
925 covers Walnut Creek, Concord, Pleasanton and Antioch and 10 more places in California. In the 925 area, phone numbers are given out most in Contra Costa County, then Alameda County.
What state is area code 925 in?
California. 925 is a California area code on Pacific Time.
What cities use area code 925?
The places holding the most 925 prefixes are Walnut Creek, Concord, Pleasanton, Antioch, Livermore, Dublin, Danville and Martinez, out of 14 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.
Which phone company owns area code 925?
No single phone company owns 925. NANPA's records show Pacific Bell (AT&T) holds the most 925 prefixes, 206 of 640, followed by AT&T Mobility and Level 3 (Lumen). Numbers move between carriers, so check one exact number with a carrier lookup.
What time zone is area code 925 in?
925 is on Pacific Time.
When did area code 925 start?
925 went into service on March 14, 1998, when it was split off from 510.
How do I dial a 925 number?
Local calls need 1, then the area code, then the number: 1-925-555-0142.
Is 925 a toll-free number?
No. 925 is a regular area code for Walnut Creek and Concord in California, not a toll-free one. The toll-free codes in North America are 800, 833, 844, 855, 866, 877 and 888.
What area codes are near 925?
The closest are 510/341 (Oakland, California), 650 (Palo Alto, California), 408/669 (San Jose, California) and 415/628 (San Francisco, California), measured between the centres of each area.
Who called me from a 925 number?
Enter the full 10-digit number in the lookup above. It returns the listed owner where there is a public record, where the number is registered, and whether it is a mobile, a landline or a VoIP line.
Is area code 925 a scam?
925 is a real California area code, so the code itself is not a warning sign. Scam callers fake local-looking numbers on purpose, so judge the call by what the caller asks for, and look the number up before calling back.
Put this lookup on your site: our free area code widget takes two lines of code and shows any US area code's state, time zone and local time.
Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.