Yes, there's a CYE episode about this. But I was sitting in the living room of my girlfriend's parents' house yesterday evening and the Mum was on the phone to a friend at 10.30pm.
I've always advocated a cutoff of 9pm as people do private stuff post-9pm, right? What's your cutoff time? How would you feel if someone calls you at 10pm?
*only applies to landlines, mobiles are a grey area.