/mcplpExtensionID A pointer to a structure of type LINEEXTENSIONID. If the service provider for the specified dwDeviceID supports provider-specific extensions, upon a successful negotiation, this structure gets filled with the extension identifier of these extensions. This structure contains all zeros if the line provides no extensions. An application can ignore the returned parameter if it does not use extensions. The Cisco Unified TSP extensionID specifies 0x8EBD6A50, 0x138011d2, 0x905B0060, 0xB03DD275. lineNegotiateExtVersion The lineNegotiateExtVersion function allows an application to negotiate an extension version to use with the specified line device. Do not call this operation if the application does not support extensions. Function Details LONG lineNegotiateExtVersion( HLINEAPP hLineApp, DWORD dwDeviceID, DWORD dwAPIVersion, DWORD dwExtLowVersion, DWORD dwExtHighVersion, LPDWORD lpdwExtVersion ); Parameters hLineApp The handle by which the application is registered with TAPI. dwDeviceID The line device to be queried. dwAPIVersion The API version number that was negotiated for the specified line device by using lineNegotiateAPIVersion. dwExtLowVersion The least recent extension version of the extension identifier that lineNegotiateAPIVersion returns and with which the application is compliant. The high-order word specifies the major version number; the low-order word specifies the minor version number. dwExtHighVersion The most recent extension version of the extension identifier that lineNegotiateAPIVersion returns and with which the application is compliant. The high-order word specifies the major version number; the low-order word specifies the minor version number. lpdwExtVersion A pointer to a DWORD-sized location that contains the extension version number that was negotiated. If negotiation succeeds, this number falls between dwExtLowVersion and dwExtHighVersion. Cisco Unified TAPI Developers Guide for Cisco Unified Communications Manager, Release 15 and SUs 180 Basic TAPI Implementation lineNegotiateExtVersion