CenturyLink in Sioux Falls, SD
These numbers are located in the city of Sioux Falls part of Minnehaha county. There are a few other subcodes that cover this area as well so take care not to confuse them.
Minnehaha county is situated in South Dakota and operates CT (UTC -06:00) time. This number group covers the 57104, 57117, 57105, & 57109 zip codes.