Area code 357 – California
357 has served California since 2025, split from 559. It is still largely empty: 9 of 786 number blocks allocated. Onvoy / Inteliquent is the largest holder with 55.6% of blocks, ahead of Other CLEC / VoIP at 33.3%. It shares its geography with overlay codes 559, so local calls take all ten digits.
- State
- California
- In service since
- 2025
- Time zone
- Pacific
- Shares area with
- 559
Who holds 357 number blocks
Share of the 9 assigned NXX blocks (1.1% of the 786 possible), across 5 carriers. This is share of number blocks, not of subscribers.
- Onvoy55.6%
- Other CLEC / VoIP33.3%
- Verizon11.1%
Rate centers in 357
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 9.
Timeline
- 2025 357 goes into service, split from or overlaid on 559.
More about 357
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 357
What state is area code 357?
California. It covers the same area as 357/559.
Which carrier owns 357 numbers?
Onvoy / Inteliquent holds the largest share of assigned number blocks at 55.6%. The rest is spread across 2 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 357?
NANPA records the local dialing plan for 357 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
NANPA dialing note for this code: “1+10D”. Reviewed by the data desk. Spotted an error? Request a correction.