As I mentioned already, seeing as the country you may visit does not use that band exclusively it means that even if you were to visit you will still be able to use your phone, roaming on the other networks for both 2G and 3/4G. In fact, you will still be able to make calls with a quadband phone on T-Mobile USAs network since it's only T-mobiles 4G network that is 1700 (AWS). So in the end it make no difference to the user. If they want to make calls, they can, if they want 3G/4G data then it will roam on other available networks.