TAPI lineAccept

I've created a program using TAPI interface, and here is it's fragment:

void AcceptThread(LPVOID lpVoid)
{ g_lAcceptID = lineAccept((HCALL)lpVoid, NULL, 0);
  g_hevtAccept = CreateEvent(NULL, FALSE, FALSE, NULL);
  WaitForSingleObject(g_hevtAccept, INFINITE);
  g_lAcceptID = 0;
  CloseHandle(g_hevtAccept);
  if(g_lAcceptResult == LINECALLSTATE_CONNECTED)
   {
   }
  else
   HangUp();
}

VOID FAR PASCAL lineCallbackFunc(HANDLE hDevice, DWORD dwMsg,
                                 DWORD dwCallbackInstance, DWORD dwParam1,
                                                 DWORD dwParam2, DWORD dwParam3)
{ switch(dwMsg)
   { case LINE_CALLSTATE:
       switch(dwParam1)
          {
              case LINECALLSTATE_OFFERING:
              AddToLog("Ring");
            RunThread((LPTHREAD_START_ROUTINE)AcceptThread, (LPVOID)hDevice);
               break;
              case LINECALLSTATE_ACCEPTED:
              AddToLog("Call accepted");
        }
       if(g_lAcceptID != 0)
         { g_lAcceptResult = dwParam1;
           SetEvent(g_hevtAccept);
         }
   }
}

My program receives ring notification, starts lineAccept() in separate thread,
lineAccept() returns Ok, but modem doesn't really answer the call.