These people are incescent in calling a minimum of once per day. They have an option where they state they won't call back, but they do anyway. Every time I attempt to talk to a real person, they hang up. My guess is that they continue this harrassment until people give up. I have no clue what would happen at that point because I never discuss my finances to unknown parties ... and telling them that also results in a hang up and a new call the following day.
The phone numbers vary from local (i.e. displayed without an area code) to toll-free numbers to identifications such as Caller.