Finally talked to someone on their fourth call here.
Yes - its some sort of mortgage thing, either a 'lead hunter' or an outright scam.
They had my name and address, but asked about my 4.5% mortgage - on a house that I am renting and that has no mortgage.
So their database is probably just names of people that have not moved in a long time.
Since I am on the DNC list - they are either pure scam, or lead hunters breaking the law.
Either way - do not deal with them!