If you enable it. This feature might be use in situation when you don't want your employee use BBphone to call to or receive call from personal number and lock the application to not allow them to change the numbers in control rule.

My latest build not enable this feature because of it may take several hours to check every screens and because of UI still constantly change. (Decide to protect or not protect last active screen if you press red key or go to home screen or receive incoming call and in other possible use case)