Award of Grant Money using Friends Internet messaging account

Received an IM from an old classmate (Brad Porter) whom I had just friended on FaceBook telling me he had just received a windfall via UPS Courier and saw my name and picture in the list he had to sign.  It then escalated when I challenged the identity of the person messaging me, to them giving me a telephone number (240-339-3102) and requesting I contact the agent immediately then IM him back.  I know this is a scam, but don’t know what to do next.