I just got a call/hangup from this number. So far, since I've dropped my landline I've been surprised that my junk calls haven't gotten too bad. But when I get calls like this, I create a new contact from the number. Then I pick the most obnoxious ringtone I have (right now a dog bark) and add it as the ringtone. Then when a call like this comes in, I can immediately decline and ignore it. As I get additional uninvited numbers popping up on my phone, I just add them as new numbers to my "barking dog" contact. It doesn't make them go away, but it does lessen my stress and I get a perverse pleasure from clicking the decline button or hanging up on the call!