Probably nothing as long as you don't give them any information. It does, however, confirm you have a working phone number which may lead to more calls.
Best advice, get a call blocker ir don't answer calls from unknown numbers. Tere is NO LAW requires you to answer any phone call.
Got a call threating jail time if I did not come up with 5,200 dollars to settle out of court for tax fraud! I told them I would only pay cash because I do not deal with credit cards. They told me I could drive to New York and they would pick me up at the airport! Then I asked for their address so then I could just send them a check, they told me I had to go to dollar tree and put the money on an Apple ITunes card to transfer it, what a joke!
Left me a computer voice message threating me. Telling me to call them back or good luck for when this situation unfolds on me! What situation is what I'd like to know??? I'm not calling back!!