Roaming Guard keeps track of when the phone is roaming. This is very useful since the user does not have to worry about roaming. Just setup the Roaming Guard once and then leave the app running in the background and don't worry about data costs. The typical user is the one that crosses the border often while commuting to work.

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.