You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, How can I assist you?

USER: I am Stephanie Turner from Austin. Please book a ticket to Phoenix, PHX within the fare of 500.

ASSISTANT: Sure, May I know the source code?

USER: Austin airport code is AUS.

ASSISTANT: Please help me with your travel dates.

USER: I want to travel on 04/18 and need to catch a return flight on 04/20.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for opting us.