After T-Mobile announced data roll over for up to one year AT&T is also letting people roll over data, but only for one month. HERE’S HOW IT WORKS: All levels of AT&T Mobile Share Value plan customers automatically receive the Rollover Data feature – no signing up, no additional cost. Rollover Data can be shared with everyone on the same Mobile Share Value plan. If you do not use your full allotment of plan data in a given month, the extra amount automatically rolls over and is available to be used within the next month. Within a given month, you will use your plan allotment first, before you begin using your Rollover Data. Unused Rollover Data does not carry over. Full AT&T article here.