Stop answering them and unknown numbers and they will. They love numbers that have an answer of some sort, ones that do not, not so much and it becomes a waste of their time calling them.
Other
4
Apr 8, 2016
Another annoying call. No answer when you pick up and they call and call and keep calling...
Other
5
Apr 14, 2016
Automated Political Research polling. Bah! Humbug!