lineGetNumRings

  • 项目

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

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 Values

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 function is for TAPI version 2.0 and later.

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

Requirements

OS Versions: Windows CE 1.0 and later.
Header: Tapi.h.
Link Library: Coredll.lib.

See Also

lineSetNumRings | LINE_LINEDEVSTATE

 Last updated on Saturday, April 10, 2004

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