In the past I have seen phones with some settings options missing e.g. hotspot, tethering. I am on a Vodafone UK contract so in theory should otherwise be able to use a Voda locked one. But I don't want to lose anything. My S6 is sim-free and unlocked and everything works including tethering. Presumably one can also unlock them, for a fee. Does rooting facilitate unlocking? I always root my phones.