I believe this setting is either shown or not depending on the carrier settings currently downloaded to the phone. My Verizon sim, whe on the Verizon network, won't show the network settings menu. I am willing to bet if I was roaming on another carrier or inserted a foreign SIM card, the menu would be enabled. Certai. Features are disabled out of the box for certain carriers on certain devices. It's always been that way on cellphones. With Motorola phones back in the day, people were able to use seem editing in order to show or hide carrier settings or menus. I believe this is a similar circumstance.