You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I am looking to book a flight ticket to meet my friend in Chicago. can you help me for booking a flight ticket from IAH to ORD?

ASSISTANT: Sure, I am here to help you. Can you please provide your journey dates?

USER: My travelling dates are Apr 19 and Apr 21.

ASSISTANT: Do you have any connection limit preference?

USER: I need a single connecting flight.

ASSISTANT: May I know your airline preference for this trip?

USER: No.

ASSISTANT: Do you have any other specifications?

USER: I prefer to book a economy class.

ASSISTANT: May I know your good name please?

USER: My name is Edward Miller. Just now I have changed my decision, please search a flight in business class.

ASSISTANT: Edward Miller, there are no flight services are available on this route with your preferences.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for contacting us.