Just got the calls - three in a row.  First 2 from "Dallas Caller" and third from "Dave"

I have no unpaid debts and an 850 credit score.  These clowns are off shore phone thugs.  They have no capacity to follow up on any threat and are beyond US jurisdiction so you can call whomever you want but they won't go away.

Write your Senators in DC and ask that the US bind foreign countries to crack down on these operations in our "free trade" treaties.  If enough Senators hear these kinds of complaints (they keep databases on issues) then something may happen someday.  Otherwise nothing you can do but block and ignore.  Or pick up the phone and tease them / take up their time (ask questions like "what is a debt?" or "who are these police people you are talking about?")