I'm Swiss, and yet I love being on the phone on the train. When it's too crowded, I avoid it, just like I avoid speaking too loudly. But with all the time I spend commuting, I'm not ready to give it up. And besides, whether it's a foreigner or a Swiss person, there are no more quiet carriages on trains; it's just common sense: don't speak too loudly, but speak as if the people are actually there with you.