Silent your phone for short amount of time, for example if you are going into a meeting now you can set the time when your meeting will, when you click save it will start silent mode and when it hits the ending time you set it will turn back to normal mode automatically.
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Instructions
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Start Silent Mode - To start silent mode all you need to do is click the menu button on your phone which will bring up a dialog at the bottom of the screen to allow you to add a time.
Delete Time - To delete a time all you need to do is press and hold down the time and a button will pop up asking you if you want to delete, click it and the time will be deleted.

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