如何使用Asterisk-java进行保持/取消保持？

Question

使用java-asterisk连接到AMI后，我创建一个呼叫：

  OriginateAction originateAction;
    ManagerResponse originateResponse;
    getEvent event = new getEvent();
    SipShowPeerAction peer = new SipShowPeerAction();
    peer.setPeer("phone1");
    managerConnection.addEventListener(event);
    originateAction = new OriginateAction();
    ParkAction park = new ParkAction();
    originateAction.setChannel("SIP/mark");
    originateAction.setCallerId("<6002>");
    originateAction.setContext("default");
    originateAction.setPriority(new Integer(1));
    originateAction.setExten("1304");

    managerConnection.login();
    managerConnection.addEventListener(event);
    originateResponse = managerConnection.sendAction(peer);

    originateResponse = managerConnection.sendAction(originateAction, 30000);
    Thread.sleep(3000);
    park.setActionId(originateAction.getActionId());

    managerConnection.logoff();

我想使用Asterisk-java来保持和取消当前的通话，我在网上检查我发现我必须使用ParkAction但我真的不明白这个概念？ 如果有人有想法？