By default, unanswered calls are directed to voicemail. However, if you want to forward unanswered incoming calls to another phone number instead of going to voicemail, you can turn on the Call Forwarding No Answer feature. You can also forward all of your calls or turn on the Do Not Disturb feature.
To turn on Call Forwarding No Answer:
When you no longer want to forward unanswered calls to another phone number, you can turn off the Call Forwarding No Answer feature by clicking the Call Forward No Answer icon (the blue silhouette with the blue arrow) on the toolbar.