This is CallBar, a horizontal bar that appears at the top of the terminal that will allow you to handle calls as if they were push notifications IOS 5. Let us see in detail.
Callbar incorporates different gestures, buttons and functions so as to make it look like incoming calls native and intuitive for the user.
This is what you can read in the User Guide of the program. First, however, we tell you that it is compatible with almost CallBar all iDevices (iPhone, iPod Touch and iPad), supports both voice calls and those of FaceTime, can be used both in portrait and in landscape mode and is compatible with all firmware from 4.0 onwards (including beta 5 iPhone OS, but the preferences will not be available in App Settings to the final release of the operating system).