What about when you go to a friend's house? It all depends on how old you are and what you do with your phone. For example, if you're going over to a friend's house before going out to a club or bar, it's natural to have your phone on, as you probably want to be reached by other friends, who might be joining you at some point. But what if you are going for dinner at a friend's house, to watch a movie, or play some games? It can be seen as being rude if you're constantly on the phone while you're at your friend's place. It also disconnects you from what is happening in reality. Answering your phone or texting once or twice is not really a problem. It becomes a problem if you can't let go of it.
When we go out to dinner, cell phones are off. Interrupting a dinner with a call or text is a faux pas, no matter what your age, unless you're a teenager. Even then, most families have rules about this as well. Even with phones on vibrate, everyone can hear them. I've actually been able to wake up using a vibrating alarm.
If in any of these situations, you do get a call that's important, it's usually common courtesy to excuse yourself, and go into another room or outside to answer your phone. I find this classy and I've had to do this in the past when talking to clients at all hours of the day while I was away from work.
[header image by The Life Files]