"John" called asking for one of our employees.
May I ask what company you are calling from?  "ISC"
What is the nature of your call? "What is her job title and duties?"
I ignore his question and advise that she is not available & ask if he would like her voicemail. "What time is she out of her meeting or whatever...?"
I'm sorry I do not have that information.  Would you like her voicemail? "Uh, no.  ...uh... ok" *hangs up*