We are on the list and never get them, so if they continue to call, be sure you get their contact info and then report them to the do not call office. That's what I do when I get unsolicited calls. In fact, when I do that, they usually hang up before I finish telling them what I'm going to do. The thing is, you have to follow through with it too. I was getting stuff like that about 5 years ago, and after two calls where I went through with getting all the information and turning it in the way they suggest on the DNC list, and I never get calls from ANY solicitors for ANYTHING any more.
I usually start by asking them the information about their company. i.e. phone, where they are located, name etc, etc, etc, and I even ask the name of the person calling. Sometimes that alone will elicit an hang up. Then I tell them I am on the do not call list and that they are required to purchase that list. If they had done so, they would KNOW I am on it and wouldn't have called me. Then I tell them that I am reporting them. The do not call list actually makes it very easy to report. You go to their site, and just fill in the number, name of company and date and time.