No doubt this is a scam coming from a 312 (chicago) area code. I get these far too often to even bother answering.
They are always trying to sell you cheaper cable, electric, credit cards, insurance or anything to get a payment from you. You'll most likely be a lot poorer in 24 hrs. Its simple enough to just not answer any number you do not know. If its really important they will leave a message.
Ha, end of year pestering on my cell phone. I screen my calls and didn't recognize the number so didn't answer. They didn't have the courtesy to leave a message either.