If the screen flashes and nothing appears, the code is either blocked or unsupported on your specific firmware version.
Displays Global Certification Forum status. how+to+use+secret+codes+on+samsung+galaxy+a7+2+work
Did any specific code throw an when you tried it? If the screen flashes and nothing appears, the
Displays technical network information, including signal strength and SIM status. Call and Privacy Settings how+to+use+secret+codes+on+samsung+galaxy+a7+2+work