As usual, this is a predatory phone call from someone claiming to be either (1) a lawyer, (2) a debt collector, or (3) someone that is offering you employment/loan/grant/scholarship. A professional sounding name might be used, but it will be pronounced incorrectly and you will hear a lot of background noise as the person calling you is using either a cellular phone or voice over IP in a crowded area and the connection is bad.
Do not answer the phone if you are unsure of the number calling you. In most cases, the call from an unknown or unfamiliar Caller ID is not a wanted call. Let the caller go to your voice mail or answering machine and leave you a message. If someone wants to get a hold of you and has a legitimate reason for doing so, they will leave you a message with a verifiable call back number. In this scenario, you are often given another number (not toll-free) to call back and discuss the matter. It could be for a delinquent debt, a job opportunity, etc. Don't give the caller any non-public information to self-identify, including your social security number or mother's maiden name. Be very clear to the caller that they are going straight to jail - do not pass 'Go' and do not collect $200. You are not buying what they are selling. Hang up and move on.