Roaming Guard APP
Android 4.4.4 and lower versions:
When roaming and the network hasn't been approved during the setup, the phone will automatically turn off the data connection. When the phone is again connected to a network that has been approved, it automatically turns on the data connection.
Android 5.0 and higher versions:
Due to permission changes on the android platform it is not possible to turn data connection on and off automatically. Therefore the user will be informed via notifications when roaming happens on an not approved network. The user will then have to turn off the roaming connection manually.
As an additional feature the app has caller ID information. This is a feature that shows who is calling even though the number is not in users phone book.