The best way to make sure you don't call a number on the Do Not Call (DNC) list is to purchase a SAN, download the list, and use it to scrub numbers from your calling lists. The procedures should be similar for state DNC lists. The Federal Trade Commission (FTC) does offer a way to check up to three numbers to see if they are on the federal DNC list, but this tool is intended to be use for consumers to check if their own numbers are registered.