Is there any way to point Feature Code 313 to a File Based MOH?
system\devices and feature codes\CO Trunk Groups\92xxx\Music on Hold changes feature 313's audio.
The trunk settings are used by all calls recieved or made with that trunk group unless "Use Next Device's Audio Source" is selected.
This is true of all MOH settings.
Go to System\Devices and Feature Codes\Endpoints\Specific Endpoint\Audio For Calls Holding For This Device. You should be able to select a file-based MOH here. This should then be the background music played on that endpoint.
That works for callers to the device and the user of the endpoint when they themselves are on hold with another node. However, it does not change the source audio for the 313 feature code.