@volpeon i think that's a social issue more than a technical one. even IM platforms you'll still find people like me and i guess you who don't mind if several hours or even days pass between messages, and who've known a period where cellphones weren't as widespread nor as powerful as today so it was ok for people to just not be reachable for several hours per day.
nowadays you get people swearing at you if you don't reply within 5min...