You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Nancy Baker here.

ASSISTANT: How may I help you?

USER: I want to book a flight on the route from HOU to PHL, can you help me out?

ASSISTANT: May I know your travelling dates?

USER: My travelling dates will be from 08/17 to 08/19.

ASSISTANT: Please wait for a moment.

USER: Sure take your time.

ASSISTANT: Sorry to say, no flight is available for you.

USER: Oh! That's sad to know, thank you for checking.

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

USER: Most welcome.