Secure a Session
If an application does not want any interference by outside events for a session from TAPI or the service provider, it should secure the call. For example, in an analog environment call-waiting tones can destroy a fax or modem session on the original call.
An application can secure a call at the time the call is made or after the call already exists.
Not all service providers support use of this operation.
TAPI 2.x: See lineSecureCall.
TAPI 3.x: See ITAddress::Forward.