You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I need a direct flight, could you please help me with  booking a flight ticket?

ASSISTANT: Sure, Do you have any class preference?

USER: Yes, I need a economy class.

ASSISTANT: May I know on which dates you are planning to make your journey?

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

ASSISTANT: Kindly assign your source and destination airport codes?

USER: Ok, my airport codes are MCO and PHX.

ASSISTANT: Is there any more preferences?

USER: No, I do not have any other preferences.

ASSISTANT: May I know your name please?

USER: I am Dennis King.

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

USER: No worries, thank you for the information.

ASSISTANT: Thank you for approaching us.