Is there any possible way to block a number from texting you on the iPhone?

This guy I used to be friends with keeps texting me bad messages and it's creating problems with me and my boyfriend. Is there any way I can block this number from texting me? I have AT&T and I don't want to pay $4.99 a month for smart limits just to block one number. Is there an app or a feature on the iOS6?

Unless You are have a jailbroken device then download Blacklist from cydia it also block calls.