Hi, it's 你的名字 from 你的公司. May I (please) speak to Mr.Smith?
你好，我是x公司的xx，请问您是Smith先生吗？
对方不在或正忙
Could you please take a message? Please tell her/him that…
I'd like to leave her/him a message. Please let her/him know that…
能否请您留个消息，告诉他……
When is a good time to call?
什么时候方便我再次来电？
When is she/he going to be back?
他什么时候回来？
Could you tell him/her that I called, please?
能否转告他我找过他？
Could you ask him/her to call me back, please?
能否转告他请他回电给我？
Okay, thanks. I'll call back later.
好的，谢谢，我待会儿再打来。
有事说事
I'm calling to ask about/discuss/clarify…
I just wanted to ask…
I'm calling about/because…