Snom phones with version 8.x show a dark screen with the text DND when Do not disturb is on, like this:
The Snom D785 and D385 run version 10.x, and in version 10.x this screen is not there by default. You can however implement this with some simple steps.
We will need the DND image, you can find it attached. If the phone has access to the internet, you can just use link http://downloads.snom.net/documentation/snom_screenover_dnd.png. Otherwise you need up upload the image to a local HTTP server.
1. Click on Action URL settings. Enter the following:
Please replace user:pass with the HTTP username and password of your phone. If you are using a local HTTP server, you also need to replace "http%3A%2F%2Fdownloads.snom.net%2Fdocumentation%2Fsnom_screenover_dnd.png" with your local link.
2. Click on Preferences -> Appearance, and set "Background Color" to "242 242 242 50". This will change the transparency of the background in order to see the DND image behind it.
Now the custom image should get set whenever you enable DND, and then it will be cleared when you disable DND: