Most people, if they are on public transport and get a phone call, are strictly Irish about it: they mutter into the handset, not wanting those around them to know their business. They are also, presumably, wishing to exercise a bit of consideration for their fellow travellers. There are few things more annoying than having someone else’s shouted conversation intrude into your thoughts; especially as there isn’t even much satisfaction to be achieved by eavesdropping on it. You don’t know what the person on the other end of the line is saying, and often, the person on the train or bus yelling, “Really? That’s what I said. Oh stop, she’s a dose”, doesn’t give you enough to work with.
Yet, in my experience, the number of people having loud private conversations…