Never ever answer calls that do not show a name or a business you actually deal with, and even then be leery. Your bank and other institutions will not call you over and over. They won't call you on a weekend.
So turn down the ringer volume and just don't answer. After a while their stats will your number never answers. And if more people did this, they would get pissed off at whoever sells them phone lists.
I talk with someone and it's for windows and doors something like that .. They're supposed to come at my house tomorow and make an estimate but they cancelled my appointment ...