Ok a bit confused here. I read from news that CDMA iPhone5 (like Verizon's) can be used in GSM network? Does it also work the other way around? And then there are 2 GSM models. I plan to use it with T-mobile and also carriers in overseas as I travel to Asia a lot. Which one should I buy? If I buy CDMA version, can I use it in LTE overseas and LTE T-Mo?