I bought a Galaxy S5 and on any phone if you enter the USA you get 2 clocks, 1 for your home time and 1 for your current location. However with my s5 that didn't happen, it's like it didn't even know I was in the US. It wasn't connecting me to a US Phone company (like T-Mobile) so I was unable to use Mobil Data, I have Roaming turned on so I don't know what's happening
Read more: Why can't I use Mobil Data outside of my country?