function enables an application to query which notification messages the
application is set up to receive for events related to status changes for the
specified line or any of its addresses.
| HLINE hLine,
| LPDWORD lpdwLineStates,
| LPDWORD lpdwAddressStates
A handle to the line device.
A bit array that identifies for which line device status changes a message is
to be sent to the application. If a flag is TRUE, that message is enabled; if
FALSE, it is disabled. Note that multiple flags can be set. This parameter uses
the following LINEDEVSTATE_ constants:
Device-status items other than those listed below have changed. The
application should check the current device status to determine which items have changed.
The switch tells the line to alert the user. Service providers notify
applications on each ring cycle by sending LINE_LINEDEVSTATE
messages containing this constant. For example, in the United States, service
providers send a message with this constant every six seconds.
The line was previously disconnected and is now connected to TAPI.
The number of outstanding call completions on the line device has changed.
This line was previously connected and is now disconnected from TAPI.
The "message waiting" indicator is turned on.
The "message waiting" indicator is turned off.
The line is connected to TAPI. This happens when TAPI is first activated or
when the line wire is physically plugged in and in service at the switch while
TAPI is active.
The line is out of service at the switch or physically disconnected. TAPI
cannot be used to operate on the line device.
Maintenance is being performed on the line at the switch. TAPI cannot be used
to operate on the line device.
The line has been opened by some application.
The line has been closed by some application.
The number of calls on the line device has changed.
The terminal settings have changed.
The roam mode of the line device has changed.
The battery level has changed significantly (cellular).
The signal level has changed significantly (cellular).
The line's device-specific information has changed.
Items have changed in the configuration of line devices. To become aware of
these changes (for example, the appearance of new line devices) the application
should reinitialize its use of TAPI. The hDevice
parameter of the LINE_LINEDEVSTATE
message is left NULL for this state change as it applies to any of the lines
in the system.
The locked status of the line device has changed.
The device is being removed from the system by the service provider (most
likely through user action, through a control panel or similar utility). A
LINE_LINEDEVSTATE message with this value will normally be immediately followed by a LINE_CLOSE
message on the device. Subsequent attempts to access the device prior to TAPI
being reinitialized will result in LINEERR_NODEVICE being returned to the
application. If a service provider sends a LINE_LINEDEVSTATE
message containing this value to TAPI, TAPI will pass it along to
applications which have negotiated TAPI version 0x00010004 or above; applications
negotiating a previous API version will not receive any notification.
A bit array that identifies for which address status changes a message is to
be sent to the application. If a flag is TRUE, that message is enabled; if
FALSE, disabled. Multiple flags can be set. This parameter uses the following
Address-status items other than those listed below have changed. The
application should check the current address status to determine which items have
The device-specific item of the address status has changed.
The address has changed to idle (it is now in use by zero stations).
The address has changed from being idle or from being in use by many bridged
stations to being in use by just one station.
The monitored or bridged address has changed from being in use by one station
to being used by more than one station.
The number of calls on the address has changed. This is the result of events
such as a new inbound call, an outbound call on the address, or a call changing
its hold status.
The forwarding status of the address has changed, including the number of
rings for determining a "no answer" condition. The application should check the
address status to determine details about the address's current forwarding status.
The terminal settings for the address have changed.
Returns zero if the request is successful or a negative error number if an
error has occurred. Possible return values are:
LINEERR_INVALLINEHANDLE, LINEERR_OPERATIONFAILED, LINEERR_INVALPOINTER,
LINEERR_RESOURCEUNAVAIL, LINEERR_NOMEM, LINEERR_UNINITIALIZED.
TAPI defines a number of messages that notify applications about events
occurring on lines and addresses. An application may not be interested in receiving
all address and line status change messages. The lineSetStatusMessages
function can be used to select which messages the application wants to
receive. By default, address status and line status reporting is disabled.
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