It could be any number of operations. In fact the number that appears on caller id may not be the number that is calling. These operations are know for spoofing their number in an effort to hide the actual number.
They are rude and when I asked them to identify who is calling, they said they would call back later. There is obviously something NOT RIGHT about whomever is using this number. They asked for my wife and when I simply asked who is calling, they would not answer and hung up. Weird
The first call asked for my wife saying it involved a murder and needed to talk with my wife, who I've been divorced from for 6 months. 2 days later the same number called for her saying they were doing a political questionnaire.
This number keeps calling my parents and will not talk. When we call the number back, the message is that "the number you have called is not a working number."