A few questions: Are the different GSM bands (1800, 1900, etc...) for cell calls and data? or are there different bands used for cell and data? Which brings me to why I'm concerned. I desperately need a new iPhone. I'm buying a 6S when they arrive here in the US. But, I'm moving to the UK in a few months. I won't have time to wait for the sim-free model to come out (unless Apple releases them at launch). So my plan was to buy a T-Mobile phone from Apple as it seems they are basically unlocked. Are the bands of the T-mobile phone from Apple the same as the sim free? Thanks.