It's now confirmed that Apple's Do Not Disturb feature which is available for iPhone, iPod Touch and iPad on iOS 6 doesn't work. The buzz first started on MacRumours, where users complained that the Do Not Disturb was working ahead of the time that they had set it for.
One user in Japan wrote, I am in Japan so it is 2013, and I am finding that my iOS devices (iPhone 4 and iPad 2) are showing "Do Not Disturb" even though it is outside of the time I set for them. Not sure if this is related to the new year. Reloading the devices does not help and the software is up-to-date.
The Do Not Disturb feature lets users turn off notifications, calls, etc while they're sleeping or are during a meeting.
Now it seems Apple has put admitted to the problem and asked users to manually turn the feature on and off. You can view Apple's support page here.
Apple's page states: Do Not Disturb scheduling feature will resume normal functionality after January 7, 2013. Before this date, you should manually turn the Do Not Disturb feature on or off.
To turn off the scheduling feature, tap Settings > Notifications > Do Not Disturb and switch Scheduled to Off.