A：May I speak to the head of the household?
      我可以请户主听电话吗？

B：May I ask who's calling?
      请问你是谁？

A：This is Susan with Jiaotong University student.I am calling on behalf of the Private Teacher Company. May I have your name, sir?
      我是交通大学的在校生苏珊，我代表家教公司给您打电话。请问您贵姓？

B：My name is Li.
      我姓李。

A：Excuse me, Mr. Li. Do you have children, Mr. Li?
      打搅了，李先生。您有孩子吗？

B：Yes.
      有。

A：Great. I believe you must care for his educations.
      太好了。我相信你肯定很关心他的教育吧。

B：Yes.
      是的。

A：You probably heard about it. We have private teachers in our holiday.We will help your children in learning lessons in their free time. We are running a special offer on this holiday. You might want to know more about it.
      或许你已经听说过。我们交大的学生在假期间做家教。我们可以帮助您的孩子在他们空闲时学习功课。 我们在这个假期有个特价优惠。我想你肯定想多了解点吧。

B：yeah.
      是的。

1. 代表（亦使用 in someone's behalf，主要用于美国英语中）
    If you do something on someone's behalf, you do it for that person as their representative. The form in someone's behalf is also used, mainly in American English.

behalf在线翻译

    e.g. She made an emotional public appeal on her son's behalf...
           她代表儿子动情地发出了公开呼吁。
    e.g. Secret Service officer Robin Thompson spoke on behalf of his colleagues.
           特工处官员罗宾·汤普森代表他的同僚发表了讲话。

2. 为（某人）；替（某人）
    If you feel, for example, embarrassed or angry on someone's behalf, you feel embarrassed or angry for them.

    e.g. 'What do you mean?' I asked, offended on Liddie's behalf.
           “你什么意思啊？”我问，替利迪感到愤愤不平。