Although most cellular carriers do not charge airtime when someone leaves a voice mail message for you, they do charge you when you retrieve messages from you cellular phone. So you retrieve the message right away, usually from your cellular phone. You can reduce your cellular phone bill significantly by retrieving your messages from a landline phone. Just understand that the phone call you make to tell everyone about Bobbie's achievement has a cost associated with it. Sometimes, those conversations are better reserved for the dinner table.
Every cellular phone has a power button.
You can turn the phone off, if you want. If you're afraid of missing important phone calls, get voice mail on your cellular phone.