While using the Reach UC App it's possible DND mode might be enabled on your phone. To verify please open the app at look at the top left hand corner of your phone
If you see the DND icon in the top left hand corner of the App, you'll need to disable it.
Tap on the Reach UC Icon in the top left hand corner and a new window will show up
Tap on the slider so that it disables the DND mode
You will see the DND icon remove when you tap on the slider
Then you can take anywhere outside the box to go back to the App and DND mode will be disabled.
To renable DND please follow the steps in reverse.