it was actually my first phone interview EVER, so I was quite worried. the guy asked me three questions: first something easy on options. I didn't answer since had zero experience at that time. second was something easy on probability, involving Bayesian formula. I was too freaked at the time because of the first question. got a bit confused and didn't solve all of the parts (after I put down the phone, it was a 5 minute question, actually) third question was "how to make a fair coin out of a biased one". that's a very famous question which unfortunately I didn't know at that time. I tried coming up with something but with a questionable success. the guy didn't give me any hints at all, and so the interviewed was finished. that was a quick and obvious rejection, no questions asked. the interesting information is that one year later they don't even give me an opportunity to interview again -- now I'm in the system, and they rejected me immediately. the moral is -- if you're really interested in them, be sure you are ready before you interview. one lousy bad morning, and you get "stupid" on your tab.