You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help  you?

USER: Can you please help me to book a flight from PHL to AUS?

ASSISTANT: Can I know your travelling dates?

USER: My travel dates are Sept 19 to 21.

ASSISTANT: Do you have specification?

USER: I prefer direct flight.

ASSISTANT: Can I know your name?

USER: I am Lisa Hernandez.

ASSISTANT: Sorry, there is no flight with your travelling dates.

USER: No problem, thank you for the information.

ASSISTANT: Thank you.