Area code 605

About area code 605

NANPA lists 605 as an in-service geographic area code for South Dakota, first put into service on January 1, 1947. It is not part of an overlay, so every number in its territory starts with 605. It is in the Central and Mountain time zone. The places with the most assigned exchanges include Sioux Falls, Rapid City, Aberdeen, Spearfish, and Watertown. By population, its largest named places are Sioux Falls, Rapid City, Aberdeen, Brookings, and Watertown.

Where 605 numbers are local

605 holds 100% of the 745 central office codes assigned in South Dakota, the most of any code in the state. 212 Census places could be matched to rate centers with 605 exchanges; the most populous are Sioux Falls (209,000), Rapid City (79,894), Aberdeen (27,919), and Brookings (24,555). Each place page lists the exact prefixes and carriers for that town.

Ten-digit and seven-digit dialing in 605

According to NANPA's dialing-plan data, local calls within 605 are dialed as ten digits (area code plus number) and toll calls as 1 plus ten digits. Because local calls need the area code, business cards, signage and website copy should always show the full ten-digit number. NANPA's dialing-plan note for this code reads: "1+10 digit permissible at service provider discretion."

Who holds 605 exchanges

92 carriers hold the 745 central office codes assigned in 605. Qwest Corporation has the most, with 104 (14%). 366 of the codes (49%) are pooled, meaning the code holder shares blocks of 1,000 numbers with other carriers instead of using all 10,000 itself. The code holder is not necessarily the carrier serving a given number today, since numbers can be ported between providers.

Where 605 numbers are rated

NANPA assigns each central office code to a rate center, the local calling area that decides whether a call is local or toll. 605 has codes in 269 rate centers. Rate center names in the file are abbreviations; where one matches a Census place, the table links to that city's local-number page.

How full is area code 605?

An area code has 800 possible central office codes that start with 2 through 9, a few of which are reserved (such as N11 service codes and 555). 745 are assigned in 605, 93% of 800. 63 were assigned in 2020 or later.

Getting a 605 number for your business

Callata is a business phone system priced at $99 a month with 5 users included, then $20 per additional user. Callata Office includes up to 3 local business numbers, unlimited inbound calling, 1,500 pooled outbound US and Canada minutes per user each month, a browser softphone that can also ring your cell, voicemail with transcription, call recording with AI summaries, business-hours routing and E911 on every number.

Porting a number you already use in area code 605 is free, and business texting is available once the carrier registration (10DLC) is approved; the registration carries a one-time $49 fee. Which specific numbers are open in a given area code depends on carrier inventory at the time you sign up.

AI agents are optional: an AI receptionist or scheduler can pick up when the team is busy or closed, take a message, send a text or email, or transfer the call. They draw on prepaid AI minutes ($0.25/minute), disclose that they are AI, and outbound AI calls require prior consent and are limited to 8am–9pm.