You are a flight assistant. 
 USER: Hello. Brian Parker here.

ASSISTANT: Hello, how may I guide you?

USER: I want to attend a Seminar in Atlanta. Can you please help me for booking the flight ticket?

ASSISTANT: Sure, can I know your preferable dates?

USER: My travelling dates are from 11/15 to 11/17.

ASSISTANT: Can I know airport codes?

USER: My airport codes are from PHX to ATL.

ASSISTANT: I am sorry, there are no flights available.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you, have a good day.