iPhone/iPad- Sounds of the iPhone

Settings>Sounds

In this part of Settings, you can control what ringtone you have and if you want it enabled.
When the phone is on silent you can control whether or not you want it on vibrate.
There is also a volume control of how loud you want your ringer. You can also control this with the side buttons on the left side of you phone if you have Change with Buttons turned on.
You can also pick which type of ringer you want for a phone call and what sound you want for messages.

Under this settings you can decide whether you want a sound or not for you Voicemail, E-mail, Calendar, etc.