Good morning, @jmbacon ...
Many of the SMS notification options have been disabled on your "Notifications" screen of Canvas for quite some time now. I've been able to find some of the documentation supporting this decision by Instructure. In all of these links, look for the areas with "SMS" or similar wording (though these links should take you directly to the spot on the page that you're asking about):
I hope this information will be of some help to you. Sing out if you have any other questions...thanks!
