They called me and left a voicemail saying I should call them back for personal reasons that they did not disclose. They never said who they were or what they do. When I called they refused to disclose any information before I could verify my full name, address, social, and date of birth. They said they did n't have a physical address to give me when I asked for it. 

To me this sounds like someone who makes a living out of identity fraud. 
