I'm not sure how old you are but if you are old enough, it wouldn't hurt to start building up some credit. Some day you will need some good credit and having no credit will hurt you. Try to sign up for a credit card. It may not be a good one and it may have a high interest rate, but as long as you pay it off every month on time it doesn't matter. If your worried about all the horror stories of people going crazy with it and going into debt, then don't bring it around with you and only use it for your AT&T bill. Once a month you pay off your credit card balance of $80-100 (whatever your bill is) and you will gradually start building credit. I guess this would depend on the person and their ability to not get carried away but this is what I would do.
To put it into perspective, I'm now 25 and for the past 3 years I've made almost every single purchase on my credit card. I've learned to know how much I'm spending and to know my limits and I've always paid off my bill in full every month, so I've paid no interest. I now have a very high credit score and have almost 100,000 miles (~$1,000) built up on my credit card which can almost pay for a full free vacation for myself. I'm not recommending that you do this now, but I'm saying you should start off small and learn how to manage your money first and then maybe someday use your credit card more often.