Not sure if this was posted already, I searched....I found this the other day on how to bring up a "hidden" service menu on the S3, no root needed. Allows access to bunch of testing features to see if your phone isn't working or is working correctly.....
Accessing the Service menu
The Service menu is activated through a sort of code that you enter into the dial pad of the phone. To get started:
Link ref: How to uncover and use the hidden Service menu on the Galaxy S3 | Android Central
Accessing the Service menu
The Service menu is activated through a sort of code that you enter into the dial pad of the phone. To get started:
- Start your Phone app
- Get to the Keypad screen
- Type in: *#0* #
Link ref: How to uncover and use the hidden Service menu on the Galaxy S3 | Android Central