I answered, and after a brief pause they started talking about an online survey related to java (I'm a java developer). When I said "what survey?" they said "a survey you filled out online, do you remember?" When I said "what survey?" again, they said they're a recruiting firm. I did not fill out any survey and I'm on do-not-call registry. so I hung up. It's an automated system playing recordings, but it's very cleverly done, and almost fooled me.