Tap Profile and then tap Distraction Eliminators.
Make a selection from the Allow incoming calls options:
No one - Reject all calls
Favorites - Choose a select group of people
Contacts - Everybody in your Contacts
Everyone - Everyone, including callers not in your Contacts.
Enable and Edit the Auto Reply Message
OtoZen automatically sends an SMS message informing the caller that you are driving when a call is rejected. You can set the message that the caller receives.
An Auto Reply Message is required for No One, Favorites, and Contacts incoming call options.