1. Rollover Data for AT&T Prepaid: available only on select plans. Monthly unused high-speed data from your plan allowance rounds up to the nearest MB and carries over for one 30-day renewal period when your plan renews on time. Unused Rollover Data automatically expires after one renewal period, or with any plan change (such as changing monthly plan or balance expiration). Rollover Data is used after your monthly high-speed plan allowance. Data: high-speed 4G LTE data service available on smartphones only. Basic/messaging phones are capable of 2G or 3G speeds. Data usage exceeding high-speed allotment will result in reduced data speeds of up to 128Kbps for the rest of your 30-day term. Actual speeds vary by device and location. Service provided by AT&T Mobility.