Most of the get and set operations deal with one component of information only. The phoneGetStatus function returns complete status information about a phone device to an application.
As mentioned earlier, whenever a status item changes on the phone device, a PHONE_STATE message is sent to the application function. This message's parameters include a handle to the phone device and an indication of the status item that changed.
An application can use phoneSetStatusMessages to select the specific status changes for which it wants to be notified. Correspondingly, phoneGetStatusMessages returns the status changes for which the application wants to be notified.