You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: Brandon Roberts here. I need a flight ticket from Philadelphia to Atlanta. Can you please book the ticket for me?

ASSISTANT: Sure, I am here to help you. Could you please share your travelling dates to search a flight?

USER: Sure, I am willing to travel on the dates of 06/19 and 06/21.

ASSISTANT: Ok, may I know the airport codes please?

USER: The preferred regional airport codes are PHL and ATL.

ASSISTANT: Ok, please wait for a while. Sorry Brandon, there are no flights found on your requested dates.

USER: It's ok, I will reach some other booking agency. Thank you for searching.

ASSISTANT: Thank you for approaching us, have a nice day.