Report them to FCC. Even if they were a legit debt collector there is a standard message that is required by ALL debt collectors before they even try to speak with you and these people obviously don't have that knowledge. They're probably sitting in a kitchen at home trying to con people with either older dead debts or none at all. KNOW THE LAW!!!
Was a robo call saying they received paperwork about an unsatisfactory account. This is a scam. It comes from an unkown caller. Call originated from Seattle WA