Call centers have many vectors that use the same basic call flow, but are unique because each requires unique announcements, route-to destinations, holiday tables, Vector Routing Table (VRT) indices, and conditional limits. With VDN variables, you can create a generic call flow vector. The unique items are designated on the VDN screen using VDN variables. VDN variables reduce the number of vectors, ensure common flows and ease of administration when the flows need to change due to unforeseen events such as problems with trunking, staffing, or messaging.