I didn't answer and the caller didn't leave a message, but
I am confident that this is Portfolio Recovery Associates, as everything described on this page fits their MO perfectly (refusing to identify themselves, no message, etc...).
Thing is, I do owe "them" money, but have very little confidence that paying them off will get rid of them.
Portfolio recovery steals informations,buys fraudulent informations from fraudulent sources,because portfolio recoveries are felons who can't get employments and never will So please make extra efforts to file lawsuits and reports their whereabouts to law enforcements.
If you have a smartphone - you can create a contact for "Scam" & set the caller ID to block them; then they can't leave a message (not like they would) nor can they get through & make your phone ring. The phone basically ignores them & blocks them from contacting your from that number. I've done this & it works great! :)