From the main menu, select Setup > Sounds.

Mute All

Mutes all device tones.

Volume

Sets the device volume level.

Message Rec.

Sets the tone that sounds when you receive a message.

Message Sent

Sets the tone that sounds when the you send a message.

Critical Alert

Sets the tone that sounds when the device announces a critical alert.

Power Off

Sets the tone that sounds when you turn off the device.