You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello.

USER: I am John Thomas.

ASSISTANT: How may I help you for today?

USER: As its business trip, please book a ticket from Phoenix, AZ-PHX to Houston, TX-HOU.

ASSISTANT: Sure, when you are start your journey?

USER: My departure will be on 11/18 and return by 11/20.

ASSISTANT: Please wait for a minute.

USER: Sure.

ASSISTANT: Sorry, there is no flight is available for you.

USER: Thanks for the help.

ASSISTANT: Thank you for choosing us.