Specifying Media Modes
The ability of an application to deal with inbound calls or to be the target
of call handoffs on a line is determined by the value used for the dwMediaModes
parameter of the lineOpen
function. With this function, the application indicates its interest in
monitoring calls or receiving ownership of inbound calls of one or more specific media modes
, or of any
(unspecified) media mode, as described in the following cases:
- An inbound call of a certain media mode is given to the application that has opened the line device for
that particular media mode. A single application may specify multiple flags
simultaneously to handle multiple media modes.
- An application that wants to handle calls for which the actual media mode
present has not yet been determined would turn on the unknown media bit as a parameter of lineOpen.
- An application that wants to handle calls of any media mode would indicate
this capability by turning on all of the media bits that are supported on the line (which can be obtained from LINEDEVCAPS).
All applications that have opened a line device in any mode are notified about
certain general statuses and events occurring on the line device or its
addresses. These include the line being taken out of service, the line going back
into service, the line being under maintenance, an address coming in use or going
idle, and an open or close operation being executed on the line. An application
that does not care about a certain message can use the lineSetStatusMessages
function to filter the message. Most such status messages are disabled by
default; an application would need to call lineSetStatusMessages
to enable them.
The media modes specified with lineOpen
add to the default value for the provider's media mode monitoring for initial
inbound call type determination. This means that the dwMediaMode
settings of all applications with the line open are OR
ed together, and that union becomes the default media detection on the line.
function modifies the mask that controls LINE_MONITORMEDIA
messages but does not affect the default media detection enabled on new
incoming calls. It is necessary for an application using lineMonitorMedia
to call it to establish media monitoring on every new call in which it is
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