You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: My name is Nicholas Smith. I am looking to book a flight ticket to meet my friend in Phoenix. Can you help me for booking a flight ticket from IAD to PHX?

ASSISTANT: Sure, may I know your trip dates?

USER: My travelling dates are June 29 and July 01.

ASSISTANT: Do you need any other specifications?

USER: I need a single connecting flight.

ASSISTANT: May I know at want time do you need flights?

USER: My return time is afternoon.

ASSISTANT: Can I know your class preference?

USER: Any class is fine for me.

ASSISTANT: Sorry to inform you that, there are no flights available.

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

ASSISTANT: Thank you for opting us.

USER: Welcome.