I have received, on the same day, multiple calls from multiple phone numbers - with exactly the same message threatening me with litigation. All calls with same "case" number, all delivered by the same halting female voice. Pretty stupid even for a scam operation. Just ignore, provide NO response and block each number when there are multiple numbers.
i called the number back from my work phone not my cell phone and they said it was the IRS. i have received the same call at least twice a week. No clue as to why they would be calling!