[Maggie Klenke]

VDN is a term specific to Avaya systems. It is the lead phone number in the switch that is used to start a call down a defined pathway with certain rules and agent groups to be accessed. It is particularly important in the design of skills-based routing plans. So a call on a specific phone number enters your ACD from the public network on a trunk, and your ACD has instructions to direct calls on that trunk to a specific VDN. Alternatively, the calls may go to a menu system to select what the caller wants and that selection designates which VDN the ACD will go to. That is how sales calls get to the sales agents and service calls get to the service agents.

Nortel has a similar tool and call it a CDN. Other vendors have their own terminologies. It is always tough to look up terms that you think are industry-wide only to find they are vendor-specific.