I believe she said "Civil Investigation Unit"... it wasn't for me, but someone in my house. I just told them that was not his number and they said "ok" and hung up. Did not sound legit. I tried to call back and it kept ringing with no type of answer at all.
Telling me that they need to deliver legal documents and that I need to return their call by the end of the day to avoid legal action. Reported number to the FTC as scammers.