If he didn't mention what Federal agency (FBI, ATF, Treasury, IRS or one of about a hundred others) he was an agent for, I would suggest you DO have a way of knowing ;-)
Call received from a recorded female message call robot stating that i had won millions of dollars from the Global International Sweepstakes and was being notified by the U.S.Claims Department! And it said congratulations!!! I am going to call them back to see what they say!.............I will update if i find out that it is a scam!!
Let me save you the time - It's a scam. Why don't you go on the internet & try to find the offices' of "U.S.Claims Department". You will also find out there is a 'fee' to collect your (fake) winnings. It is a very simple Nigerian advance fee scam. Any time you are asked to pay money to get money, it's a scam. 100% of the time, every time. When you get paid at work do they ask you to send tax money by Western Union BEFORE you get your pay check? Nope, get the picture?