You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I guide you?

USER: Eric Gonzalez here. I would like to book a ticket from HOU to IAH.

ASSISTANT: Sure, can I know your preferable dates?

USER: I am starting on 09/11 and return back on 09/13.

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

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you, have a good day.