An iPhone running iOS 6 has four possible modes to silence app notifications, phone calls and incoming messages: Mute, Do Not Disturb, Airplane mode and powered off. Often, users are confused about how these modes may affect the iPhone's native Alarm application. While it is true that some silent modes do have an effect on third-party alarm clock apps, only powering off your phone completely will disable the native Alarm application.
The mute switch on the side of the iPhone toggles the standard Silent mode of your iPhone. While in this mode, your iPhone won't make any sounds associated with applications, games or third-party alarms. The phone will vibrate on notifications only if you've enabled Vibrate mode. The native Alarm app is not affected by silent mode; thus, if you have an alarm scheduled with an alarm tone, you will hear it at the designated time.
Do Not Disturb Mode
In iOS 6, Apple introduced a Do Not Disturb mode that enables users to turn off all application notifications on the iPhone as well as incoming calls. However, you can create a VIP list of contacts whose calls will still ring the phone when you are in Do Not Disturb mode. This mode has no effect on the native Alarm app, and any alarms set will sound at the specified time.
Airplane mode turns off the iPhone's cellular radio, Wi-Fi and Bluetooth radio. This mode allows you to still use your phone for music, games and other applications while you are on an airplane. All your incoming calls, SMS messages and incoming Internet app notifications are disabled, but any alarms set in the native Alarm application will remain enabled.
Power Off iPhone
If you power off your iPhone, the device won't alert you of any notifications. Even the native Alarm app will not alert you if an alarm time is reached. This is the only mode that completely silences the iPhone and prevents notifications of any type.