US Federal. Grants Dept fraudulant call stating I was chosen to receive a $9,000 federal grant. They require a call back to their senior account manager which instructions are given to acquire a  pre-paid card, deposit $200 on the card (for identity verification) then upon giving them the pre-paid card number they will deposit $9,200 on the card. Yea, Right!! How nieve do they think we are? How do we stop them from calling?