Today I received the same exact call as Justin. I called back and the mailbox was 'full'. I have no outstanding debts, or legal issues with anyone. Sure does look like some scam. It's iritating and frustrating to see scumbags like this get away with needlessly harassing folks. Glad I found this website.
Report them to the DO NOT CALL REGISTRY. There is a link on there to report companies like this. I just reported them myself and hopefully if they get enough complaints they will look into this company.