You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you today?

USER: Can you help me to book a business class flight ticket?

ASSISTANT: Sure, I am here to help you. May I know your travel dates please?

USER: My travel dates are Dec 25 and Dec 27.

ASSISTANT: Ok, can you please mention your airport codes?

USER: My airport codes are PHX and EWR.

ASSISTANT: Ok, do you have any specifications?

USER: I would like to depart in the evening and return back in the morning times.

ASSISTANT: Ok, hold on for a moment. Let me check the best available flight for you.

USER: Sure.

ASSISTANT: May I know your name please?

USER: My name is Katherine Carter.

ASSISTANT: Sorry Katherine Carter, there are no flights available on your requested dates.

USER: No problem, thank you for the information.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.