Call Queues and Route Points

A call queue or route point is a special address within the switch where calls are temporarily held pending action. This characteristic is represented by the bits LINEADDRCAPFLAGS_QUEUE and LINEADDRCAPFLAGS_ROUTEPOINT in the dwAddrCapFlags member in LINEADDRESSCAPS. All calls appearing on such an address are awaiting action by the application, and there can be default actions that take place (for example, transfer to an agent or trunk) if the application takes no action within a defined period of time. The application must be configured by the system administrator so that it knows what actions it should take regarding calls appearing on each queue or route point address, and the amount of time available to decide on the action to take.

Applications can determine the number of calls pending in a queue or route point using lineGetAddressStatus. The lineGetCallInfo function can be used to obtain information such as calling ID, called ID, inbound or outbound origin, and so on, and used by the application to make decisions on call handling; calls can be redirected, blind-transferred, dropped, and so on, or just allowed to automatically pass out of the queue to a destination. A call goes to LINECALLSTATE_DISCONNECTED if it is abandoned. Calls go idle when they leave the queue; lineGetCallInfo can be used to read the redirection ID to determine where they were transferred.

Some switches allow calls in a queue or on hold to receive particular treatment such as silence, ringback, busy signal, music, or listening to a recorded announcement. The lineSetCallTreatment function allows the application to control the treatment. The structure delimited by the dwCallTreatmentListSize and dwCallTreatmentListOffset members in LINEADDRESSCAPS allows applications to determine the supported treatments. The dwCallTreatment member in LINECALLINFO indicates the current treatment, and a LINE_CALLINFO message with LINECALLINFOSTATE_TREATMENT indicates when this changes. The LINECALLFEATURE_SETTREATMENT bit in the dwCallFeatures member in LINECALLSTATUS indicates when changing the treatment by the application is permitted. The LINECALLTREATMENT_ set of constants defines a limited set of predefined call treatments; service providers can define many more.

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