925 area code — Walnut Creek, CA geographic

Data: NANPA public reports, current as of July 28, 2026.

State
California
Major area
Walnut Creek
Time zone
Pacific
In service since
1998-03-14
Split from
510
Active prefixes
631
Rate centers
17
Carriers
32
Projected exhaust
3Q 2051

The 925 area code covers Walnut Creek, California, Pacific time zone, and dates back to March 14, 1998. Because of number portability and VoIP, the area code tells you where the number was issued, not where the caller is right now.

NANPA lists 631 active NXX prefixes in 925, assigned to 32 carriers. 437 of those prefixes are pooled — shared between carriers in thousands-number blocks. The code spans 17 rate centers (billing localities).

Official projections put exhaust at 3Q 2051.

The dialing plan is 1+10D for home-NPA local calls and 1+10D across codes.

To check where a specific 925 number was issued, look up its six-digit prefix; to check who is actually calling, ignore the display and verify through an official callback number — caller ID is assertable and routinely spoofed.

Its parent code is 510, which it left in 1998.

Largest localities in 925

Largest rate centers in area code 925
Locality (rate center)Active prefixesAlso served by
Walnut Creek 102
Concord 88
Pleasanton 76
Antioch 65
Livermore 49
Bishop Ranch 43
Dublin-san Ramon 41
Danville 38
Martinez 21
East Contra Costa 21

FAQ

Is 925 a toll-free number?

No. 925 is a geographic code; calls are billed like any other domestic call. Toll-free codes are 800, 833, 844, 855, 866, 877 and 888.

Will 925 run out of numbers?

NANPA's current forecast projects exhaust in 3Q 2051 — decades of capacity remain.

Why am I getting spam calls from 925 numbers?

Scammers spoof recognizable area codes so calls look local or familiar. A displayed 925 number does not prove the call originated there — see our guide to spotting spoofed calls.