Requesting Call Privileges

In addition to media mode, an application can specify the call privileges it wants for the calls provided to it. With privileges, an application specifies whether it wants to monitor calls or own them. For an incoming call, only one application is selected as the owner, although all applications with monitor interest in the call are also notified about the incoming call. The usual privileges an application specifies are summarized in the following list:

• If the application only wants to monitor calls, it specifies LINECALLPRIVILEGE_MONITOR. The application will also receive monitor handles to outgoing calls placed by other applications (an application receives owner handles for outgoing calls it places itself). It will also receive MONITOR handles for calls it places itself on other instances of the same line.
• If the application wants to make outgoing calls only, it specifies LINECALLPRIVILEGE_NONE. An application that has NONE selected will not be automatically informed of incoming calls. However, it can also become aware of calls on the line with LINE_ADDRESSSTATE(numCalls) or LINE_LINEDEVSTATE(numCalls) messages. It can then call lineGetNewCalls.
• If the application wants to accept incoming calls of a specific media mode (or modes), it specifies LINECALLPRIVILEGE_OWNER and one or more relevant LINEMEDIAMODE_ settings.
• If the application is willing to control unclassified calls (incoming calls of as-yet unknown media mode), it specifies LINECALLPRIVILEGE_OWNER and LINEMEDIAMODE_UNKNOWN.
• In other cases, the application should specify the media mode it is interested in handling and set dwPrivilege to LINECALLPRIVILEGE_OWNER.

An application that wants to be informed of all calls on the line regardless of whether it can become an owner on the call can set both the LINECALLPRIVILEGE_OWNER and LINECALLPRIVILEGE_MONITOR bits. It will get call handles with owner privileges for incoming calls for which it is the highest priority application for the highest priority media mode on the call, and monitor privileges for all other incoming and outgoing calls.

An application that has successfully opened a line device can always initiate calls using lineMakeCall, lineUnpark, linePickup, lineSetupConference (with a NULL hCall parameter), as well as use lineForward (assuming that doing so is allowed by the device capabilities, line state, and so on).