Apple iPhone 4G - Manual (Page 13)

Ring/Silent Switch
Flip the Ring/Silent switch to put iPhone in ring mode or silent mode.
Ring
Silent
In ring mode, iPhone plays all sounds. In silent mode, iPhone doesn’t ring or play alerts
and other sound effects.
Important: Clock alarms, audio apps such as iPod, and many games still play sounds
through the built-in speaker when iPhone is in silent mode.
By default, when you get a call, iPhone vibrates whether it’s in ring mode or silent
mode. If iPhone is in ring mode, you can silence a call by pressing the On/Off
Sleep/Wake button or one of the volume buttons. Press a second time to send the
call to voicemail.
For information about changing sound and vibrate settings, see “Sounds and the
Ring/Silent Switch” on page 191.
13 Chapter 1 iPhone at a Glance