I have searched high and low to find out what the leaning "Cresent Moon" symbol is that is just to the left of the time on the top of the screen. I've included a screenshot of my desktop on the phone.
You are so smart! Thanks! I was hoping Apple was putting the phases of the moon next to the time. That would be kind of cool except we have a full moon now, not a quarter...
Notifications and calls are silenced in "Do Not Disturb" mode. It is a setting in iOS6, not something that is carrier dependent. Hours for DND can also be set.