You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you please help me in booking my ticket from AUS to HOU?

ASSISTANT: Sure, please provide your trip dates.

USER: Sure, my trip dates are from 12/16 to 12/18.

ASSISTANT: Do you have any other requirements?

USER: Yes, I need a direct flight.

ASSISTANT: May I know your name?

USER: My name is David Collins.

ASSISTANT: Sorry, there is no flight available.

USER: It's ok, thank you for your help.

ASSISTANT: Most welcome.