Avaya communication servers provide a vector conditional that is based on a count of the active calls to a VDN. Incoming trunk calls that route directly to the VDN by Direct Inward Dialing (DID), DCS, PRI, tie or tandem trunks, or incoming trunk calls, where the VDN is considered to be the incoming destination, are considered active calls for a VDN. Incoming trunk night service calls where the VDN is the night service destination, or calls that forward or cover to the VDN, and that have not already routed to another VDN on this communication server are also considered active calls for a VDN.

The current active VDN call count is sent to the CMS, where it can be displayed on real-time reports. Note that the count of “active” calls on the communication server is not the same as the CMS count of INPROGRESS calls in the VDN, since the definition of “active in the VDN” differs between the communication server and CMS. That is, CMS counts calls as INPROGRESS in the VDN whether they are inbound trunk calls or internal calls and regardless of whether this is the first VDN for the call or not.