When an application makes a call, a handle to the call with owner privileges is returned to the application. When the application is notified about an incoming call, it is given a handle to the call with either owner privilege or monitor privilege, depending on the privilege previously requested with lineOpen. It can also receive a handoff from another application, in which case it would receive owner privilege.
An application's call handle and associated privileges remain valid until the application takes an explicit action to change them or if it receives a LINE_CLOSE message, which closes the line. In this case, all handles to calls on the line instantly become invalid.
After a call reverts to the idle state, the application is still allowed to read the call's information structure and status. When the application has no further use for the call (and its information), it should deallocate the call handle by invoking lineDeallocateCall, which is discussed in following topics.
For more information about call logging and handing off calls to other applications, see Multiple-Application Programming.