Communication does not just means a person hears others by his phone or just by messages. It means people talking in the same subject and both of them (the person who is listening and the person who is talking, focus in the same topic. In these days communicating has changed than before.
In these days people who sit together, usually they are doing something else too, such as checking their mobiles, not just to know the time but to have fun.
Usually when a person behaves like this he prevents others to communicate with him even if he do not have any problem if they had talked to him. Most of the times, in these day people uses massages rather than calls or face to face talk. Sending messages is good but it should never replace face to face talk or calls.
When a person wants or needs to communicate with others, he should prevents himself from using anything that lets him live in another world, such as phones. Whenever a person starts to look at his phone or use it while he is sitting with others he prevents them from talking to him even if he do not mind if they did. If a person wants or is sitting with others he should be with them with his mind and body, not just his body.