You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: I want to travel in a business class flight, can you please help me out with flight ticket booking?

ASSISTANT: Ok, may I know your trip dates?

USER: Sure, I am planning to move on Dec 22 and please book my return ticket on Dec 24.

ASSISTANT: Can I know airport codes?

USER: Sure, I want to travel from OAK to IAD.

ASSISTANT: Do you have any other requirements?

USER: I would like to return in evening time.

ASSISTANT: May I know your name please?

USER: Sure, my name is Joseph Baker.

ASSISTANT: Sorry Joseph, there is no flight available on these route.

USER: Oh! Sad to hear that. Anyway, I will find another alternative. Thank you for the information.

ASSISTANT: Most welcome.