I just purchased a new cdma/gsm S4. There is an audible hisssss while making a call. On the Call options the "noise reduction" option is greyed out preventing me from toggling it (it is ON now). The Date and Time option is all greyed out and will not let me manually change them. I already r and r'd the first phone as the system was ALWAYS stuck in Headphone. This is the second try. Any help is appreciated. I already tried a hard reset. I have a note 2...really a beautiful phone and everything works. The audio is super crystal clear and the call audio is the same.