The call comes from somewhere in the US. The National Do Not Call List doesn't apply to the US. The secret is not to answer calls. My telephone company told me there are 'autodialers' out there. Obviously this is one of them. In time, they'll stop calling, but I too don't like being disturbed over this sort of thing.
Someone from this number has called 4 times today and it seems like an auto response system that responds to your answers like are you the home owner or is your heating system older that 12 years old. I said yes and she said I wasn't eligible. I called them called them back and this time and this time I was asked if the system was older that 12 years. I said no and she said thank you and hung up.