I was in bed last night at 9:40 (I know it's early but I'm up at 5). I was just about to drop off to sleep and the phone rang (and rang). When I eventually dragged myself out of bed thinking it might be a family emergency it turned out to be a family acquaintance ringing for a chat.
I am not overly bothered about this but I was just wondering what time people think is too late to ring people who aren't close family or friends.