You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am Christine Thomas. I am looking for a direct flight, could you please help me with booking a flight ticket?

ASSISTANT: May I know your travelling airport codes please?

USER: My source airport code is DCA and destination airport code is PHX.

ASSISTANT: On which dates you like to travel?

USER: I would like to take 05/13 and return on 05/15.

ASSISTANT: I am sorry no flights available on your route.

USER: That's ok, not an issue.

ASSISTANT: Thank you for choosing us.

USER: Anyways, thank you for the information.