The PHONE_CLOSE message is sent when an open phone device has been forcibly closed as part of resource reclamation. The device handle is no longer valid once this message has been sent.
PHONE_CLOSE
hPhone = (HPHONE) hPhoneDevice;
dwCallbackInstance = (DWORD) hCallback;
dwParam1 = (DWORD) 0;
dwParam2 = (DWORD) 0;
dwParam3 = (DWORD) 0;
No return value.
The PHONE_CLOSE message is only sent to an application after an open phone has been forcibly closed. This can be done to prevent a single application from monopolizing a phone device for too long. Whether the phone can be reopened immediately after a forced close is device specific.
An open phone device can also be forcibly closed after the user has modified the configuration of that phone or its driver. If the user wants the configuration changes to be effective immediately (as opposed to after the next system restart), and these changes affect the application's current view of the device (such as a change in device capabilities), then a service provider can forcibly close the phone device.
Version: Use TAPI version 1.4 and later.
Header: Declared in tapi.h.