Likely a debt collector.
After doing a skip trace on the debtor, they not only call the debtor, they call ALL OF THEIR RELATIVES.
They use the PAPERS FOR A LAWSUIT THAT'S HAPPENING SOON, but they can't tell you when, BECAUSE THERE IS NO CASE... they just want the contact information for their intended victim or for their intended victim to call them.
If the debt is older than a certain amount of time, THEY CAN'T TAKE THE PERSON TO COURT, and it's likely that by the time LOW LIFE DEBT COLLECTORS like this call from SPOOFED NUMBERS and FAKE LAW FIRMS, that this debt would qualify.
Tell them you don't know the person, but since you seem to be getting a lot of call for this person from unscrupulous debt collectors, YOU HAVE NOW HIRED REPRESENTATION, so if they'd like to give you their info, you'll be sure to have your people contact them.
If they haven't hung up....
...just be silent and breathe heavy till they hang up.