FTM or Field Test
The FTMInternal-4 app, also commonly known as Field Test, is one of the most hidden apps you can access, and there’s a reason for that. Unless you’re an engineer or a cellular service provider, chances are most of us won’t even know what in this app.
The Field Test app is meant to help you see data about your cellular operator. You can see things like your service provider, cellular service status, and band info.
Needless to say, this app isn’t for the average person, but you can still access it by using your phone app. Go to your phone, tap on the keypad, and enter *3001#12345#*. Press call, and instead of actually making a call, you’ll immediately open the FTMInernal-4 app.
It’s worth noting that you shouldn’t mess with anything inside the app. You can tap and see all the information you want, but try to leave everything as it is if you don’t have experience with it.