I have a Verizon HTC One and am confused about if I can use it abroad. I think it supports GSM as well as CDMA. Theoretically could I just buy a prepaid GSM sim card and put it in instead of the 4g one I have now? I care more about voice than data abroad. I don't want to sign up to whatever BS international plan Verizon has as I am quite sure it will be stupid expensive (maybe I am wrong). Can the phone be unlocked to allow pre paid sim cards to be used? Does rooting the phone help in any of this (I assume rooting is completely different to unlocking the phone for use on another network).