You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I have planned to book a plane ticket from IAH to CLT, can you assist me in booking?

ASSISTANT: Sure, please provide your trip dates.

USER: My journey dates are Apr 9th and Apr 11th.

ASSISTANT: Do you need any connection limit?

USER: I need to travel in direct flight.

ASSISTANT: Is there any other specifications?

USER: No.

ASSISTANT: May I know your name?

USER: William Lee.

ASSISTANT: There are no flights available on your routes.

USER: No problem, thank you for searching.

ASSISTANT: Thank you for choosing us.