South Dakota area codes
South Dakota uses 1 area code. Its code 605 has been in service since 1947. It has 745 of its 786 possible number blocks allocated, 94.8% of capacity. Across the state no single national carrier holds the most blocks: 49.1% sits with CLEC and VoIP holders counted together, ahead of Lumen at 15.4%. In the 33 days to 30 October 2026, FTC complaints named a South Dakota caller ID 236 times – 0.1% of all complaints in the window, most often 605 with 236 (327th of 422 nationally). The state spans 2 time zones (Central and Mountain); 605 crosses a zone boundary alone. NANPA records 269 rate centers in 605, and local calls take all ten digits.
The South Dakota area code
| Code | In service | Blocks used | Largest holder | Complaints | Shares area with |
|---|---|---|---|---|---|
| 605 | 1947 | 745/786 | Other CLEC / VoIP 49.1% | 236 | no overlay |
Block share is share of allocated number blocks, not of subscribers. Complaint counts cover 28 Sep – 30 Oct 2026 and reflect spoofed caller IDs as much as real calls.
How full South Dakota’s codes are
A code holds at most 786 blocks of 10,000 numbers each. When a code fills up, the administrator does not reclaim numbers – it adds an overlay, and from then on new numbers in the same area come from the new code.
Most room left
Who holds the number blocks
Counted from every assigned block in the state: 745 blocks, each with the holder NANPA recorded for it. Percentages are measured, not estimated.
| Holder | Blocks | Share of South Dakota | Largest in |
|---|---|---|---|
| Other CLEC / VoIP | 366 | 49.1% | 1 code |
| Lumen | 115 | 15.4% | – |
| Verizon | 102 | 13.7% | – |
| AT&T | 86 | 11.5% | – |
| T-Mobile | 24 | 3.2% | – |
| Onvoy | 19 | 2.6% | – |
| Bandwidth | 14 | 1.9% | – |
| Consolidated | 4 | 0.5% | – |
| Dish | 4 | 0.5% | – |
| Telnyx | 3 | 0.4% | – |
| Windstream | 2 | 0.3% | – |
| Charter | 2 | 0.3% | – |
“Other CLEC / VoIP” is not one company: it is every holder outside the national carriers counted together, which is what resellers and app-based numbers look like in the records. This is allocation, not subscribers.
Spam complaints naming South Dakota codes
FTC Do Not Call complaints where the caller ID shown was a South Dakota number, 28 Sep – 30 Oct 2026 (33 days). Caller IDs on spam calls are routinely faked, so these are complaints about the code, not calls proven to come from it.
Time zones
South Dakota is in Central, Mountain time. 605 covers more than one zone within a single area code, so the code alone does not tell you what time it is there. This code spans 2 time zones.
Frequently asked about South Dakota area codes
How many area codes does South Dakota have?
1 in service. That code is 605.
What is the oldest area code in South Dakota?
605, in service since 1947.
What time zone is South Dakota in?
It spans 2: Central and Mountain. 605 covers more than one zone within a single area code, so the code alone does not tell you the time.
Which South Dakota area code gets the most spam complaints?
605 – 236 FTC complaints in the 33 days to 30 October 2026, 327th of 422 codes nationally. Those are complaints about the caller ID shown, and spam callers routinely fake a local-looking number, so this says the code is imitated often, not that the calls come from there.
Which carrier holds the most South Dakota numbers?
No one carrier does. 49.1% of the 745 number blocks assigned across South Dakota are held by CLEC and VoIP providers outside the national carriers – resellers and app-based numbers look like this in the records. The largest named carrier is Lumen with 15.4%. This is allocation of blocks by the numbering administrator, not a count of subscribers – people keep their numbers when they switch carriers.
Do you have to dial 10 digits in South Dakota?
Yes. The code is in a ten-digit dialing area, so a local call needs the area code too. Dialing seven digits reaches a recording, not a wrong number.
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, 28 Sep – 30 Oct 2026, retrieved Nov 1, 2026
Figures on this page are counted from those files, not copied from other sites. Spotted an error? Request a correction. How we collect and check: methodology.