phoneNegotiateAPIVersion function (tapi.h)

Article
02/22/2024

The phoneNegotiateAPIVersion allows an application to negotiate an API version to use for the specified phone device.

Syntax

LONG phoneNegotiateAPIVersion(
  HPHONEAPP          hPhoneApp,
  DWORD              dwDeviceID,
  DWORD              dwAPILowVersion,
  DWORD              dwAPIHighVersion,
  LPDWORD            lpdwAPIVersion,
  LPPHONEEXTENSIONID lpExtensionID
);

Parameters

hPhoneApp

Handle to the application's registration with TAPI.

dwDeviceID

Identifier of the phone device to be queried.

dwAPILowVersion

Least recent API version the application is compliant with. The high-order word is the major version number, the low-order word is the minor version number.

dwAPIHighVersion

Most recent API version the application is compliant with. The high-order word is the major version number, the low-order word is the minor version number.

lpdwAPIVersion

Pointer to a DWORD in which the API version number that was negotiated will be returned. If negotiation succeeds, this number is in the range dwAPILowVersion to dwAPIHighVersion.

lpExtensionID

Pointer to a structure of type PHONEEXTENSIONID. If the service provider for the specified dwDeviceID parameter supports provider-specific extensions, this structure is filled with the extension identifier of these extensions when negotiation succeeds. This structure contains all zeros if the line provides no extensions. An application can ignore the returned parameter if it does not use extensions.

Return value

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

PHONEERR_INVALAPPHANDLE, PHONEERR_OPERATIONFAILED, PHONEERR_BADDEVICEID, PHONEERR_OPERATIONUNAVAIL, PHONEERR_NODRIVER, PHONEERR_NOMEM, PHONEERR_INVALPOINTER, PHONEERR_RESOURCEUNAVAIL, PHONEERR_INCOMPATIBLEAPIVERSION, PHONEERR_UNINITIALIZED, PHONEERR_NODEVICE.

Remarks

The phoneNegotiateAPIVersion function is used to negotiate the API version number to use with the specified phone device. It returns the extension identifier supported by the phone device, or zeros if no extensions are provided.

If the application wants to use the extensions defined by the returned extension identifier, it must call phoneNegotiateExtVersion to negotiate the extension version to use.

Use phoneInitializeEx to determine the number of phone devices present in the system. The device identifier specified by dwDeviceID varies from zero to one less than the number of phone devices present.

The API version number negotiated is that under which TAPI can operate. If version ranges do not overlap, the application, API, or service-provider versions are incompatible and an error is returned.

Requirements

Requirement	Value
Target Platform	Windows
Header	tapi.h
Library	Tapi32.lib
DLL	Tapi32.dll