This guy will call you sounding like he has marbles in his mouth. Leaves no detail about the message. He will try to sell you an investment into an oil field. They are telemarketer scammers.
I didn't answer. I'd like to know if/how to report this sort of call.
My tack these days is to simply not answer if I don't recognize the caller. I look them up online first, and it's almost always a telemarketer or other sales call.