Area Code 605
Local Presence for Rapid City, Sioux Falls and Aberdeen
You can increase your connection rate up to 30% by dialing from a local number.
Local Presence by Tenfold gives you one-click access from your existing phone system to a local number in the US area code 605 and more than 200 others.
Reach out to customers in Rapid City, Sioux Falls and Aberdeen.
Source: Wikipedia