lineGetNumRings (Compact 2013)

3/26/2014

This function determines the number of rings an incoming call on the given address should ring prior to answering the call.

Syntax

LONG WINAPI lineGetNumRings(
  HLINE hLine,
  DWORD dwAddressID,
  LPDWORD lpdwNumRings 
);

Parameters

• hLine
  Handle to the open line device.

• dwAddressID
  Address on the line device. An address identifier is permanently associated with an address; the identifier remains constant across operating system upgrades.

• lpdwNumRings
  Number of rings that is the minimum of all current lineSetNumRings requests.

Return Value

Returns zero if the request succeeds or a negative error number if an error occurs. The following table shows the return values for this function.

Value	Description
LINEERR_INVALADDRESSID	The address identifier is invalid.
LINEERR_OPERATIONFAILED	The operation failed.
LINEERR_INVALLINEHANDLE	The handle to the open line device is invalid.
LINEERR_RESOURCEUNAVAIL	The resources are unavailable.
LINEERR_INVALPOINTER	The pointer is invalid.
LINEERR_UNINITIALIZED	A parameter is uninitialized,
LINEERR_NOMEM	Not enough memory is available.

Remarks

The lineGetNumRings and lineSetNumRings functions, when used in combination, provide a mechanism to support the implementation of toll-saver features across multiple independent applications.

An application that receives a handle for a call in the offering state and a LINE_LINEDEVSTATE ringing message should wait a number of rings equal to the number returned by lineGetNumRings before answering the call in order to honor the toll-saver settings across all applications. The lineGetNumRings function returns the minimum of all applications' number of rings specified by lineSetNumRings. Because this number can vary dynamically, an application should invoke lineGetNumRings each time it has the option to answer a call. If no application has called lineSetNumRings, the number of rings returned is 0xFFFFFFFF. A separate LINE_LINEDEVSTATE ringing message is sent to the application for each ring cycle.

If call classification is performed by TAPI of answering all calls of unknown media mode and filtering the media stream, TAPI honors this number as well.

Note

This operation is purely informational and does not in itself affect the state of any calls on the line device.

Requirements

Header	tapi.h
Library	TAPI32.dll

See Also

Reference

TAPI Line Device Functions
lineSetNumRings
LINE_LINEDEVSTATE (TAPI)