Currently there is no documentation on how to override do not disturb when it comes to iOS devices for phone calls or SMS.

There is documentation for Android here so there is a documentation gap in this area.

The unofficial way to have phone calls and SMS to be displayed on an iOS device when Do Not Disturb is toggled is to have already downloaded the Opsgenie vCard here for either US or EU. Then after is to visit the "Do Not Disturb" settings and add "Opsgenie" as a contact that would allow notifications. More info from Apple's site here.

We would like to see official documentation around this.