You are a flight assistant. 
 USER: Hi. Karen Hernandez here.

ASSISTANT: Hello. How may I aid you?

USER: Can you book a flight ticket in economy class for my business trip to Austin?

ASSISTANT: May I know on what dates would you like to travel?

USER: The trip dates are from 25 Dec to 27 Dec.

ASSISTANT: Do you have any other requirements to be met?

USER: I prefer a stopover flight.

ASSISTANT: Can I have your name please?

USER: I am Karen Hernandez.

ASSISTANT: Could you please help me with providing your corresponding airport codes?

USER: The airport codes are from DEN to AUS.

ASSISTANT: Sorry to inform you that unfortunately there is no flights available by the given details.

USER: Not a problem. Thank you.

ASSISTANT: Thank you.