I don't really check my phone often. I miss loads of calls and text messages, so my friends have learnt not to bother with contacting me unless I call them/specifically ask them to call me when I see them.

When I'm bored, I tend to check it often to look at the time. I think it's rude when I do it/friends do it too often when we hang out. Especially if you're in the middle of a conversation with them.