You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I am Rachel Martin. I want to book a flight ticket from PHL to IAH. Could you help me in booking?

ASSISTANT: Sure, may I know your planed trip dates?

USER: My travelling date are from Dec 16-18.

ASSISTANT: Do you have any connection limit?

USER: I need 1 connecting flight.

ASSISTANT: May I know your arrival and depart timings?

USER: My return time should be in the evening.

ASSISTANT: Is there any class preference?

USER: I prefer for economy class.

ASSISTANT: Please be on hold.

USER: Ok.

ASSISTANT: There are no flights found on your specified travel dates.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for opting us.