Likely using some sort of demon dialer program that dials in numerical order. My cell is unlisted, kept very strictly private, and on the Do Not Call list but I still get scam calls. Scammers are going down a numerical list; i.e., 123-456-7890, 123-456-7891, and so on. It's that simple.
same thing, call came through last night, and again tonight. 1 minute to 9 PM. They say nothing. With all of these posts, obviously this caller is a harrasser. I think it's time to call the police. Will call AT & T tomorrow and start the process. Would encourage all others to do the same.
If you call the number back it will tell you that it is Insight Teleservices. After a few mins of talking they ask if you want to be removed from their calling list. Press 1 for yes and then enter your number. Hopefully it works. I just did this tonight.