I am currently under RingPlus and I am thinking on changing into Ting. I have a Nexus 5X, which can be both GSM or CDMA and was also bought new and unlocked. My question is, what should I choose, CDMA or GSM? I also travel to Europe where it's mostly GSM. I would like to be able to buy a local GSM sim, put it in my phone and work. If I choose CDMA in Ting, will that affect the ability of my phone to accept a GSM local sim card in Europe?