You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Larry Edwards here. I want to book a flight from HOU - PHX.

ASSISTANT: Sure, may I know your trip dates?

USER: My travelling dates will be from 12/12 to 12/14.

ASSISTANT: Sorry, there is no flight on your requested dates.

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

ASSISTANT: Thank you for opting us.

USER: Most welcome.