SMS: As long as people know how to use the silent vibrate mode which I believe not that many people are aware off exists

Internet: Yes but as said above no VOIP.

Mobile Phone: No way in hell. Some people don't even need a phone (just need to open the window - a tad difficult on planes I know) as they speak so loud that no one around them can hear themselves think. Even a ban of mobile phones in the lounges would not be a half bad idea tbh, or at least have mobile free areas (even setup a mobile phone signal blocker as they have in some cinemas) ^