CALLTYPE

The CALLTYPE enumeration constant specifies the call types used by IMessageFilter::HandleInComingCall.

typedef enum tagCALLTYPE 
{ 
    CALLTYPE_TOPLEVEL             = 1, 
    CALLTYPE_NESTED               = 2, 
    CALLTYPE_ASYNC                = 3, 
    CALLTYPE_TOPLEVEL_CALLPENDING = 4, 
    CALLTYPE_ASYNC_CALLPENDING    = 5 
} CALLTYPE;

Elements

CALLTYPE_TOPLEVEL: A top-level call has arrived and that the object is not currently waiting for a reply from a previous outgoing call. Calls of this type should always be handled.
CALLTYPE_NESTED: A call has arrived bearing the same logical thread identifier as that of a previous outgoing call for which the object is still awaiting a reply. Calls of this type should always handled.
CALLTYPE_ASYNC: An aysnchronous call has arrived. Calls of this type cannot be rejected. OLE always delivers calls of this type.
CALLTYPE_TOPLEVEL_CALLPENDING: A new top-level call has arrived with a new logical thread identifier and that the object is currently waiting for a reply from a previous outgoing call. Calls of this type may be handled or rejected.
CALLTYPE_ASYNC_CALLPENDING: An asynchronous call has arrived with a new logical thread identifier and that the object is currently waiting for a reply from a previous outgoing call. Calls of this type cannot be rejected.
async call can NOT be rejected