TSPI_lineGetDevCaps function (tspi.h)

Article
10/06/2021

The TSPI_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

LONG TSPIAPI TSPI_lineGetDevCaps(
  DWORD         dwDeviceID,
  DWORD         dwTSPIVersion,
  DWORD         dwExtVersion,
  LPLINEDEVCAPS lpLineDevCaps
);

Parameters

dwDeviceID

The line device to be queried.

dwTSPIVersion

The negotiated TSPI version number. This value has already been negotiated for this device through the TSPI_lineNegotiateTSPIVersion function.

dwExtVersion

The negotiated extension version number. This value has already been negotiated for this device through the TSPI_lineNegotiateExtVersion function. This parameter is not validated by TAPI when this function is called.

lpLineDevCaps

A pointer to a variably sized structure of type LINEDEVCAPS. Upon successful completion of the request, this structure is filled with line device capabilities information.

Return value

Returns zero if the function succeeds, or an error number if an error occurs. Possible return values are as follows:

LINEERR_INCOMPATIBLEAPIVERSION, LINEERR_OPERATIONUNAVAIL, LINEERR_INCOMPATIBLEEXTVERSION, LINEERR_OPERATIONFAILED, LINEERR_NODRIVER, LINEERR_RESOURCEUNAVAIL, LINEERR_NOMEM.

Remarks

Line device identifier numbering for a service provider is sequential from the value set by the dwLineDeviceIDBase parameter that is passed to the TSPI_providerInit function.

The dwExtVersion formal parameter indicates the version number of the requested extension information. If it is zero, no extension information is requested. If it is nonzero, it holds a value that was negotiated for this device with the TSPI_lineNegotiateExtVersion function. The service provider fills in device- and vendor-specific extended information according to the extension version specified.

The service provider fills in all the members of the LINEDEVCAPS data structure, except for dwTotalSize, which is filled in by TAPI. The service provider must not overwrite the dwTotalSize member.

The service provider must fill in all members of the LINETERMCAPS data structure or structures embedded in the varying part of the LINEDEVCAPS data structure.

After the service provider returns from the TSPI_lineGetDevCaps function, TAPI sets the dwLinesStates member of the LINEDEVCAPS structure as follows:

LINEDEVCAPS.dwLineStates |=
    LINEDEVSTATE_OPEN |
    LINEDEVSTATE_CLOSE |
    LINEDEVSTATE_REINIT |
    LINEDEVSTATE_TRANSLATECHANGE;

Requirements

Requirement	Value
Target Platform	Windows
Header	tspi.h