1. From the home screen, tap the Settings icon.
   
2. Tap Data Manager.
   
3. To change the displayed billing cycle, tap the Data usage cycle drop-down.
   
4. Tap to view the desired billing cycle.
   
5. To change the billing cycle start date, tap Change cycle.
   
6. Select the desired date, then tap Set.
   
7. To set a monthly data limit, tap Limit mobile data usage.
   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 limits.
   
8. Tap OK.
   
9. Drag the Warning marker up or down to set the level at which you will be warned about your monthly data usage.
   
10. Drag the Limit marker up or down to set the monthly data limit.
    
11. Scroll down to view data usage broken down by app.
    Note: To restrict apps from using data while running in the background, tap the Menu icon > Restrict background data.