You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Please help me in booking flight ticket from IAH to PHX.

ASSISTANT: Sure, may I know your trip dates please?

USER: My trip dates are Feb 20 to Feb 22.

ASSISTANT: Do you have any other requirements?

USER: I prefer to travel in connecting flight.

ASSISTANT: Can I know your name please?

USER: Catherine Robinson here.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Most welcome.