The phoneNegotiateExtVersion function allows an application to negotiate an extension version to use with the specified phone device. This operation need not be called if the application does not support extensions.
LONG phoneNegotiateExtVersion( HPHONEAPP hPhoneApp, DWORD dwDeviceID, DWORD dwAPIVersion, DWORD dwExtLowVersion, DWORD dwExtHighVersion, LPDWORD lpdwExtVersion );
Handle to the application's registration with TAPI.
Identifier of the phone device to be queried.
API version number that was negotiated for the specified phone device using phoneNegotiateAPIVersion.
Least recent extension version of the extension identifier returned by phoneNegotiateAPIVersion that the application is compliant with. The high-order word is the major version number; the low-order word is the minor version number.
Most recent extension version of the extension identifier returned by phoneNegotiateAPIVersion that the application is compliant with. The high-order word is the major version number; the low-order word is the minor version number.
Pointer to a DWORD in which the extension version number that was negotiated is returned. If negotiation succeeds, this number is in the range dwExtLowVersion to dwExtHighVersion.
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_INCOMPATIBLEAPIVERSION, PHONEERR_RESOURCEUNAVAIL, PHONEERR_INCOMPATIBLEEXTVERSION, PHONEERR_UNINITIALIZED, PHONEERR_INVALPOINTER, PHONEERR_NODEVICE.
The phoneNegotiateExtVersion function is used to negotiate the API version number to use. It returns the extension identifier supported by the phone device, or zeros if no extensions are provided.
In order for the application 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 extension version number negotiated is that under which the application and service provider must both operate. If version ranges do not overlap, the application and service-provider versions are incompatible and an error is returned.