The ability to play sounds for critical alerts.
- iOS 12.0+
- macOS 10.14+
- tvOS 12.0+
- watchOS 5.0+
Critical alerts ignore the mute switch and Do Not Disturb; the system plays a critical alert's sound regardless of the device's mute or Do Not Disturb settings. You can specify a custom sound and volume.
Critical alerts require a special entitlement issued by Apple.