Hello, Missus Smith, How Can I Help You?

When the person has introduced themselves, this is missus smith. What if mister smith wants to speak to tom but he's not there? You say, i'm really sorry, he's not available at the moment. Can i take a message? Or i'm afraid he's busy. Shall i ask him to call you back? Ok. And to end a converse tion, you can say, thank you for calling. Good bye.