Area codes / California / 831
The 831 area code
831 is an area code in California, in the Pacific time zone. Get a local 831 number for your business, shared by everyone who answers it, or bring the 831 number you already have.
831 at a glance
- State
- California
- Time zone
- Pacific
- In service since
- 1998
- Overlay
- None: the only code for its area
- Local calls
- Seven-digit dialing within the area code
Get a 831 business number
When you sign up for Onyx Phone, you pick a local number by area code: search 831, narrow it by the next three digits or the last four if you want something memorable, and it's yours on the spot. Which numbers are free changes daily.
The number rings everyone you assign to it, in the browser, on the iPhone and Android apps, and on desk phones, and texts from it are unlimited once US carriers approve your business. Your plan includes one number for each user, and more numbers are $5 a month.
Calling 831 customers
Local calls within 831 can be dialed with seven digits. Callers are on Pacific time, so set your business hours to match if most of your customers are here.
Calls from Onyx Phone show your business number, and once your business is verified, your caller ID name too, so 831 customers see who's calling.
Questions about area code 831
What state is area code 831?
Area code 831 is in California.
What time zone is area code 831 in?
Area code 831 is in the Pacific time zone.
Is 831 an overlay area code?
No. Today 831 is the only area code for its part of California.
Can I get a 831 business number?
Onyx Phone sells US local numbers. When you pick your number, search the 831 area code; which numbers are free changes daily.
Can I keep the 831 number I already have?
Yes. Moving a number to Onyx Phone is free on every plan and usually takes 3 to 7 business days. You answer on a temporary number until it moves.
Included on every plan
Starter is $17, Business is $29, Scale is $42 per user a month, or less billed yearly. The plan includes a business number for each user and unlimited calling and texting in the US and Canada. Every plan starts with a 7-day free trial, and moving your current number over is free.
Area code data from the North American Numbering Plan Administrator (NANPA), file of October 24, 2026.