You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: I want to book a ticket from ATL to DEN. Could you book a ticket?

ASSISTANT: Can I have your trip dates?

USER: Depart is by July, 29 and return date is July, 31.

ASSISTANT: Do you need any connection limit?

USER: I would prefer connecting flight.

ASSISTANT: Are there any other specifications?

USER: I prefer business class.

ASSISTANT: May I know your name?

USER: My name is Michael Smith.

ASSISTANT: There are no flights available on your routes.

USER: Thank you.

ASSISTANT: Thank you for opting us.