I have received these calls before. They are very well done and if you give expected answers they can be hard to detect that you are not talking to a person. I used to have a job where you always answered the phone, so, out of habit, I still do it at home. I don't even check the caller ID even though I should. That was also a habit from the old job as if I did look at caller ID there were people I would have never talked to - EVER. I would have gotten into trouble for that, so I just answered the phone.
One thing I do for all cold calls is give obtuse answers. I try to avoid using yes and no; instead I will say, that is correct, or, not really. Foreigners and computers can figure out what you mean, but it increases the lag time for their response. Once you know what, or who, you are dealing with you can really screw with them.