Some Android phones take a long time to find service after an interruption (e.g. going down to the basement). Turning Airplane Mode on then back off usually forces the system look for and regain cell service.
This app does just that, it quickly turns Airplane Mode on, then off. All you should really see is service reconnect. The Airplane Mode icon should not be seen - it's that quick.
Permissions used: Write settings: Airplane Mode is the setting (understandably) modified.
Note: Android 4.2 and newer don't allow Airplane Mode to be set by downloaded apps, so I have limited this app to 4.1 and older devices.