on the phones keypad dial: **583385## You will then see the option to enable only CDMA. after doing this it will say the action will take effect after the phones next reboot. Reboot the phone and it will now use 1X forever until you go back in there and turn LTE back on. To turn 4G back on you are going to want to select Enable Global Mode. This will allow LTE and CDMA. If you select Enable LTE only it will turn on 4G but turn off CDMA meaning no phone calls.