I agree with the other 2 posters. You flat out told him you wanted a buddy to mess around with, no committment. So he did exactly that. He won't call you unless he wants something now, so expect a couple times a month, if that, depending how many other people he's got to do this with, and don't expect to hear from him again if he starts dating someone.
IMO, there's no such thing as "friends with benefits". If you're friends, you're friends and wouldn't want to ruin it, and wouldn't let anything jepordize it. The minute you start sleeping with someone without committment, it turns into casual sex, and that tends to run the relationship. The main reason for hanging out and talking, becomes hoping to end up in bed together by the end of the day/night. This type of arrangement ruins friendships, speaking from personal experience.