Have an iPhone 7. Traveling to UK soon for long vacation. The VZ international plans are expensive due to long vacation adn expectation of lots of texting, calling and probably about 10G of data use. Can I buy and install a SIM card in the UK that will work on my phone? I have confirmed that my phone is unlocked. I got "scared" because I was told incompatible networks between CDMA and GSM woudl rule out UK sim cards. I also have in iPhone 6s - same question. Can i get that Sim card in US or do I have to buy it in UK?