a Qt4/Qt5 based GUI front end to libgammu that can send USSD codes and read text messages on supported devices.
A screenshot of the application can be seen from the following link: https://github.com/mhogomchungu/ussd-gui/blob/master/icons/ussd-gui.jpeg
download page is: https://github.com/mhogomchungu/ussd-gui/releases
useful documentation: http://wammu.eu/docs/manual/c/hints.html
The application's FAQ page is at: https://github.com/mhogomchungu/ussd-gui/wiki/Frequently-Asked-Questions