Regardless of which coach I choose to sit I don't want to have to hear other people's music or whatever they are doing on their devices that emits sound. Kids games are the worst as the music is extremely repetitive and gets irritating very quickly. It is perfectly reasonable to expect people to use headphones.
As for phone calls I would expect people to refrain in the quiet coach and do so quietly in any other carriage. I, and I expect most if not all other passengers, do not want to have listen to half of a phone call. I much prefer to travel in relative peace.