iPhone comes with ringtones that sound for incoming calls, Clock alarms, and the Clock timer. You can also purchase ringtones from songs in the iTunes Store. See iTunes Store at a glance.
Set the default ringtone. Go to Settings > Sound > Ringtone.
Assign different ringtones for the special people in your life. Go to Contacts, choose a contact, tap edit, then tap Ringtone.
Turn the ringer on or off. Flip the switch on the side of iPhone.
Important: Clock alarms still sound when the Ring/Silent switch is set to silent.
Turn vibrate on or off. Go to Settings > Sounds. See Sounds and silence.