From the Connections tab in Settings, tap Data usage.
Tap Billing cycle and data warning.
From this screen, you can limit your data usage and set up alerts for when you're reaching your data usage limits for the current month.
Tap or slide the Set data warning switch to ON.
Tap Data warning.
Enter your preferred data usage warning, then tap Set.
Tap or slide the Set data limit switch to ON.
Tap Data limit.
Enter your preferred data limit, then tap Set.
You can also turn off mobile data when you're in areas where you don't want to use any data.
Tap Start billing cycle on.
Select your preferred data usage cycle reset date, then tap Set.
We recommend you match this date to the date your billing cycle starts to more accurately manage your data.
You've completed the steps!
