Mobile Communication Etiquette

Many people have cellphone in the world, and I also have cellphone.
This time, the theme is " Mobile Communication Etiquette ".
I think this theme is interesting.
I have a story about this theme.

One day, I took a train which prohibits the passenger from using cellphone.
I knew that, so I didn't use my cellphone, however,
some people in the train use thier cellphone, but, nobody said
" This train prohibits the passenger from using cellphone " .
Suddenly, a old man who sat next to me shouted!
" We must not use cellphone in this train!! "
This old man stood up and shouted again.
Tha train quited down. People who used cellphone started to stop using cellphone,
but, a young woman didn't stop using cellphone because she listened to music,
so she didn't notice that a old man shouted in the train.
A old man approached her, and then, he hit her and shouted.
She was suprised and stopped to using cellphone with angrily.

When I saw a man shouter everyone, I thought he is too angry,
however he was true. It is a woman that made a mistake.
Actually, cellphone is very useful, but we should keep TPO.
We sometimes misundertand TPO.
We should judge when we can use it and when we can't use ir.
It is necessary for us to think about the usage of convienient things.