Area code 510 – California
510 has served California since 1991, split from 415. All but a handful of its 786 number blocks are allocated (785 of 786), so it is effectively exhausted. AT&T is the largest holder with 48.0% of blocks, ahead of Verizon at 13.8%. It shares its geography with overlay codes 341, so local calls take all ten digits. 775 FTC complaints named a 510 caller ID in the 33 days to 30 October 2026, putting it 113th of 422 codes with five or more complaints.
- State
- California
- In service since
- 1991
- Time zone
- Pacific
- Shares area with
- 341
Who holds 510 number blocks
Share of the 785 assigned NXX blocks (99.9% of the 786 possible), across 32 carriers. This is share of number blocks, not of subscribers.
- AT&T48%
- T-Mobile14%
- Verizon13.8%
- Lumen5.6%
- Onvoy4.7%
- Bandwidth3.7%
- Other CLEC / VoIP2.9%
- TPx2.3%
- Comcast1.5%
- Spok1.4%
- Peerless1%
- American Messaging0.5%
- Charter0.4%
- Windstream0.1%
Spam complaints naming 510
FTC Do Not Call complaints where the caller ID was a 510 number, 28 Sep – 30 Oct 2026 (33 days). Caller IDs on spam calls are frequently spoofed, so these are complaints about the code, not calls proven to originate in it.
Rate centers in 510
NANPA allocates number blocks to rate centers and records their names abbreviated to ten characters, so these are NANPA's codes rather than place names – CHAMPAURBN is Champaign-Urbana, NWYRCYZN01 is a New York City zone. We show them unchanged instead of guessing at the full names. Showing the largest 5 of 13.
Timeline
- 1991 510 goes into service, split from or overlaid on 415.
More about 510
Separate pages for the questions that need their own answer: what time it is there, what the complaint data says, who holds the number blocks, and how the code compares with the one it shares its area with.
Frequently asked about 510
What state is area code 510?
California. It covers the same area as 341/510.
Can I still get a 510 number?
Only from recycled stock. 785 of the 786 available blocks are already allocated, so new numbers in the area normally come from the overlay codes (341/510).
Is a call from 510 a scam?
Not by itself. 510 drew 775 FTC complaints in the 33 days to 30 October 2026, 113th of 422 ranked codes – mid-pack or lower. Spam callers spoof caller IDs, so the only useful check is the full number.
Which carrier owns 510 numbers?
AT&T holds the largest share of assigned number blocks at 48.0%. The rest is spread across 3 other carriers. This is share of number blocks, not of subscribers – people keep their numbers when they switch carriers.
Do I need to dial 10 digits in 510?
NANPA records the local dialing plan for 510 as “1+10D”.
Sources and verification
- NANPA – NPA Database (npa_report.csv), file date 11/01/2026, retrieved Nov 1, 2026
- NANPA – CO Code Assignment Records, All States (utilized), file updated 11/01/2026, retrieved Nov 1, 2026
- FTC – Do Not Call Reported Calls Data, 25 daily files 28 Sep – 30 Oct 2026, retrieved Nov 1, 2026
NANPA dialing note for this code: “1+10D”. Reviewed by the data desk. Spotted an error? Request a correction.