This is the "lower your interest rate" robocall scam. Just google that and you'll see what it is. I always answer it and mess with the guy to waste their time. That way less people will be scammed. If everybody could answer, and play along (but don't give real info) for about 5 minutes we can put these scams out of business, as the method will no longer be profitable.
Me: Hello?
Machine: This is a call from Cardmember Services. We are calling about your credit card account. There is nothing wrong with your account and we are calling to offer an interest rate reduction on your credit card. Press one to speak with an agent.
Me: <presses one>
Agent: Hello? (Sounding impatient)
Me: Hi, I'd like to be removed from your calling list. You do not even know my name or which card I own. Take me off the damn phone list
Agent: Hangs up