I want to force all of our 8841 and 8851 phone to have the same wallpaper/backgound. I have created the thumbnail image and full size and uploaded them as well as the list.xml. I can go to any phone and select Settings - Wallpaper and see it as an option.
I modified the Common Phone Profile that these phones use by disabling Enable End User Access to Phone Background Image Setting, checked Override Common Settings for Background Image and set that field to Desktops/800x480x24/FileName.png. I save then apply config and the phones no longer have the wallpaper option in settings but the background image does not change. I have rebooted and reset a test phone with no change.
I followed this Cisco document
Phones know where to get the files, you don't need the whole path, just the name of the image.
I'm working on the same process using just the image name in the field and it won't seem to force the background setting.
I've tried the filename.png and filename with no extension. Both result in no change. If I enable user access to background images I can manually select the background so it is working on the TFTP server.
Make sure you have it like this:
To be clear, I am running CUCM 11.5 with 8851 phones. I have unchecked the "Enable End User Access to Phone Background Image Setting". I am using Background.png for the "Background Image" field with the override option checked.
I then save, apply changes, and reset the phones. The phones reboot and the option to change the background goes away, but the background image is as it was prior to the change.