       SippSurfaceUnref surfacelist|ALL
              Delete  the  handles  in the list surfacelist which
              are associated with surfaces.  This lowers the ref-
              erence  count  on the surface.  The data associated
              with the surfaces will not  be  deleted  until  the
              objects that reference them are deleted.  If ALL is
              specified, then all surface  handles  are  unrefer-
              enced.
