I hold a sony ericsson w950i mobile..
Some cell phone providers have a service explicitly about $5 a month where you can block numbers and control how several minutes are used on each phone line, etc. Call ATT and see what they can do for you. They might be capable of block that one number for free. Of course, that won't stop him from calling you on other phone lines. If worse comes to worse, you might just have to renovate your number.Who i activate my internet on phone..
AT&T have a service where you pay monthly and you can next control who can text / call you...Call AT&T and they will make clear to you all about the service.