def METHOD_NAME(self, cbfnc, filter):
    self.__networkchange_cbfnc = cbfnc
    if None == self.__subscription:
        self.__subscription = self.__dbuscon.add_signal_receiver(self.__networkchange_callback,
                                                                 'NetworkChange',
                                                                 'net.openvpn.v3.netcfg',
                                                                 'net.openvpn.v3.netcfg')
        self.__manager_intf.NotificationSubscribe(dbus.UInt32(filter.value))