Area codes / South Dakota / 605
The 605 area code
605 is one of the original 1947 area codes in South Dakota, in the Central and Mountain time zones. Get a local 605 number for your business, shared by everyone who answers it, or bring the 605 number you already have.
605 at a glance
- State
- South Dakota
- Time zone
- Central and Mountain
- In service since
- 1947
- Overlay
- None: the only code for its area
- Local calls
- Dialed with all ten digits (area code and number)
Get a 605 business number
When you sign up for Onyx Phone, you pick a local number by area code: search 605, 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 605 customers
Local calls in 605 are dialed with all ten digits: the area code, then the number. 605 spans the Central and Mountain time zones, so the local time depends on where the caller is.
Calls from Onyx Phone show your business number, and once your business is verified, your caller ID name too, so 605 customers see who's calling.
Questions about area code 605
What state is area code 605?
Area code 605 is in South Dakota.
What time zone is area code 605 in?
Area code 605 covers places in the Central and Mountain time zones, so check which one a caller is in before you call early or late.
Is 605 an overlay area code?
No. Today 605 is the only area code for its part of South Dakota.
Can I get a 605 business number?
Onyx Phone sells US local numbers. When you pick your number, search the 605 area code; which numbers are free changes daily.
Can I keep the 605 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.