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lineGetDevCaps function

Applies to: desktop apps only

The lineGetDevCaps function queries a specified line device to determine its telephony capabilities. The returned information is valid for all addresses on the line device.

Syntax

Copy

LONG WINAPI lineGetDevCaps(
  HLINEAPP hLineApp,
  DWORD dwDeviceID,
  DWORD dwAPIVersion,
  DWORD dwExtVersion,
  LPLINEDEVCAPS lpLineDevCaps
);

Parameters

hLineApp

Handle to the application's registration with TAPI.

dwDeviceID

Identifier of the line device to be queried.

dwAPIVersion

Version number of the Telephony API to be used. The high-order word contains the major version number; the low-order word contains the minor version number. This number is obtained by lineNegotiateAPIVersion.

dwExtVersion

Version number of the service provider-specific extensions to be used. This number is obtained by lineNegotiateExtVersion. It can be left zero if no device-specific extensions are to be used. Otherwise, the high-order word contains the major version number; the low-order word contains the minor version number.

lpLineDevCaps

Pointer to a variably sized structure of type LINEDEVCAPS. Upon successful completion of the request, this structure is filled with line device capabilities information. Prior to calling lineGetDevCaps, the application must set the dwTotalSize member of this structure to indicate the amount of memory available to TAPI for returning information.

Note If the size parameters in the structure are not correct, there is a possibility that data could get overwritten. For more information on setting structure sizes, see the memory allocation topic.

Return value

Returns zero if the request succeeds or a negative error number if an error occurs. Possible return values are:

LINEERR_BADDEVICEID, LINEERR_NOMEM, LINEERR_INCOMPATIBLEAPIVERSION, LINEERR_OPERATIONFAILED, LINEERR_INCOMPATIBLEEXTVERSION, LINEERR_RESOURCEUNAVAIL, LINEERR_INVALAPPHANDLE, LINEERR_STRUCTURETOOSMALL, LINEERR_INVALPOINTER, LINEERR_UNINITIALIZED, LINEERR_NODRIVER, LINEERR_OPERATIONUNAVAIL, LINEERR_NODEVICE.

Remarks

Before using lineGetDevCaps, the application must negotiate the API version number to use, and, if desired, the extension version to use.

The API and extension version numbers are those under which TAPI and the service provider must operate. If version ranges do not overlap, the application, API, or service-provider versions are incompatible and an error is returned.

One of the members in the LINEDEVCAPS structure returned by this function contains the number of addresses assigned to the specified line device. The actual address identifiers used to reference individual addresses vary from zero to one less than the returned number. The capabilities of each address can be different. Use lineGetAddressCaps for each available <dwDeviceID, dwAddressID> combination to determine the exact capabilities of each address. Note that an address identifier is permanently associated with an address; the identifier remains constant across operating system upgrades.

Requirements