You need to also keep in mind most states have their own DNC list as well as the federal one.
You can call most anyone you have an existing business relationship with, i.e. a seller or a buyer.
You can also call them up to 18 months after that business relationship ends, i.e. listing expires, they buy a house.
The federal lists and laws supercede all state laws so even if someone is not on your state's list but on the federal one you cannot call them.
http://www.ftc.gov/bcp/conline/edcams/donotcall/index.html Here's a good little DNC list quiz.
http://www.realtor.org/rmoquiz2.nsf/DoNotCall?OpenForm Unless you can pass this quiz you better not call anyone except your mother. :p