At 1 PM ET, Microsoft releases a new update for Windows Phone 8.1. But changes are minimal. The second update, the first one came in May and that was just an improvement in battery life. This update feature was unclear, but some report shows a change in boot screen Icon, and take Quite Hours from Cortana and put it into the setting.
Windows Phone 8.1 Preview Update 12393
Stay tune for more information about this update!