1. From any screen, swipe down from the notification bar.
   
2. Tap Wireless.
   
3. Tap Mobile Network.
   
4. Tap Data Usage.
   
5. To turn on data usage limits, tap the Set mobile data limit checkbox.
   
6. If turning data roaming on, tap OK.
   
7. Set and adjust the data limit by moving the two white dots.
   Note: When the mobile data limit is active and has been reached, the mobile data block will remain in effect until mobile data is manually re-enabled on the device, the limit threshold is changed to a higher value, or a new data usage cycle begins. If you set data usage limits on your device, they do not communicate with AT&T systems. You will still receive AT&T system generated notifications as you approach your data plan limits.
   
8. To change which billing cycle you are viewing usage for, tap the Data usage cycle drop-down list.
   
9. Tap Change cycle.
   
10. Scroll to the desired reset date.
    
11. Tap Set.