This app is simply a quick shortcut to the mobile 'Network operators' settings, that usually would require 5 clicks in the settings menu. With a single click you'll be searching for mobile networks operators.
Should this shortcut not work for your smartphone, please send us details about your device and its Android version (hoping there's a solution for it)
Comments proving the correct functioning on your smartphone are obviously very welcome!
*** This does NOT work for DUAL SIM smartphones. ***