510 area code
Where the 510 area code is, its overlay and how to dial a +1 510 number from anywhere.
The 510 area code is in Alameda, California, United States (Pacific (PT)). To call from abroad: +1 510 555-0123. It is an overlay, so all 10 digits are dialled.
The 510 area code is a geographic North American Numbering Plan (NANP) code covering Alameda, California. It has been in service since 25-Apr-1990 and sits in the Pacific (PT) time zone.
How to dial a 510 number
+1 510 555-01231 510 555-0123510 555-0123Cities in the 510 area code
A 510 number is usually in one of these places in California — 2 counties.
Other California area codes
Frequently asked questions
Where is the 510 area code?
The 510 area code is in Alameda, California, United States (Pacific (PT)).
Is 510 an overlay area code?
Yes. 510 overlays the same region as 341, 415, so callers dial all 10 digits.
Do I have to dial 10 digits for 510?
Yes — dial the area code plus the seven-digit number.
How do I call a 510 number from another country?
Dial your exit code (or +), then 1, then 510, then the number: +1 510 555-0123.
Source: NANPA numbering plan. An area code covers a region, not a precise address — a 510 number does not pinpoint a street or ZIP code.
Number holders in area code 510
Each prefix (the three digits after the area code) is assigned by NANPA to one telephone company. 800 prefixes are in use in 510, shared by 35 companies. The largest holders:
| Company | Prefixes | Share |
|---|---|---|
| Pacific Bell | 278 | 35% |
| New Cingular Wireless PCS, LLC | 78 | 10% |
| T-Mobile USA, Inc. | 65 | 8% |
| Cellco Partnership Dba Verizon Wireless | 60 | 8% |
| Metropcs, Inc. | 45 | 6% |
| Onvoy, LLC | 37 | 5% |
Source: NANPA central office code assignments. A number keeps its original prefix when it is ported to another carrier.
Complaints about 510 numbers
- Reports to the FTC, last 30 days
- 565
- Recorded messages or robocalls
- 49%
- Rank among area codes
- #150 of 670
- Most reported subjects
- Other (297)
- Dropped call or no message (74)
- Reducing your debt (credit cards, mortgage, student loans) (56)
Period Aug 26 – Sep 24, 2026. These are the numbers shown on the caller ID of the reported calls; many are spoofed and do not belong to the real caller.
Source: US Federal Trade Commission, Do Not Call reported calls data (daily files).
All US area codes United States +1 Map of area code 510 — cities & rate centres