Set a warning to control monthly data usage and fix a threshold not to exceed: - open "Settings" app , - tap on "Data usage", - enable "Cellular data",* - tap on "Billing cycle", - tap on "Billing cycle" to enter your invoiced period, - enable "Set data warning" then tap on "Data warning" then and enter your settings, - enable "Set data limit" then tap on "Data limit" and enter your settings.**