Secret menu in Samsung

It could be work on any Galaxy... The trick is the next. If you select the call menu and press the next combination: *#0*# you can acces to a secret menu with a lot of configuration to your smartphone. In this menu you can test elements of your mobile, to check its functioning, or simply out of curiosity.  You can check the operation of the loudspeaker, the camera, the colors it reproduces. Although the most useful option is the sensor, which allows us to check if the touch screen works correctly anywhere on the mobile. Only passing the finger will draw a line, and we can see if this line is created or not.