The lineShutdown function disconnects the application from TAPI. If this function is called when the application has lines open or calls active, the call handles are deleted and the equivalent of a call to the lineClose function is automatically performed on each open line. (It is better for applications to explicitly close all open lines before invoking lineShutdown.) If shutdown is performed while asynchronous requests are outstanding, those requests are canceled.
An application that has registered as an Assisted Telephony request recipient should de-register itself by calling lineRegisterRequestRecipient, using the value FALSE for the bEnable parameter.