They use an auto-dialer that just keeps dialing numbers in sequence. They don't know home phones from cell phones from business phones, nor do they care. They don't pay any attention to the national Do Not Call list, nor to their own list they claim to maintain. Entering your number on their automated DNC list only gets it added to a list of real phone numbers they can sell to others.
Considering all this, their disregard for federal law and their rudeness to people they are soliciting, do you want to trust them enough to do business with them? I didn't think so...
What can you do? Keep them on the phone as long as you can by asking them to tell you about what they can do for you -- without giving them any real info about you. Just waste their time like they waste yours.