I frequently travel by train on business, and if I find that I am in the quiet carriage, I put my phone on to silent, with vibrate, so if I get a call I can go into the section between carriages to answer it. (I do need to, because it may be our P.A. calling to advise of a change of meeting time etc)
What I do find frustrating when booking tickets on-line, is that you are given options for "quiet carriage" , or "no preference" In other words you cannot actively choose not to be in the quiet carriage! Quite often my colleague and I will need to take calls, discuss or rehearse the presentation etc, and find very awkward to do so if w have been booked into the quiet carriage. (Although it is not always as quiet as it's suposed to be, too have suffered hearing either the bass lie ot the tinny top noise of what people are listening to through their earpieces. I have even been tempted to tap them on the shoulder and say "I don't think this is their best track, do you?"
When we have enough notice for a meeting, we can sometimes find bargains on first class tickets! Bliss! Plus depending on which provider you are travelling with, can actually mean saving, as a lot of the refreshments are free, plus you can use the first class lounge at the station (At Paddington this means really nice free sandwiches, coffee, cake tea, coffee, yummy nuts, fruit, bottled water etc)