You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am George Lewis.

ASSISTANT: OK.

USER: I am planning to visit Houston Space Centre with my friends at Houston, HOU. Could make a reservation from Phoenix, PHX?

ASSISTANT: Sure. On which dates would you like me to book a flight ticket for you?

USER: I want depart on 04/17 and return date is on 04/19.

ASSISTANT: Do you have any specifications?

USER: I need a stopover.

ASSISTANT: Ok, please wait for some time.

USER: Sure.

ASSISTANT: Thanks for waiting. Sorry, there are no flights found with your specifications.

USER: Ok, thank you for informing me.

ASSISTANT: Thank you for reaching us.