交换设备使提交诸如通话保持、三方通话等通话控制功能成为可能，同时也提供对外设和服务(如声邮)的访问。

Switching equipment makes possible the delivery of call-control features such as call hold and three-way calling, while also providing access to peripheral equipment and services, such as voicemail.

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如果你一定想要把手机置于耳朵上，要确保两只耳朵交替使用并且尽量控制通话时间越短越好。

If you must put the phone to your head, make sure to switch ears regularly and keep the conversation as short as possible.

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在旅程期间，如果需要的话，乘客可以按下一个按钮和控制台的工作人员通话。

During the journey, a passenger can press a button to speak to the controller if necessary.

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