You are a flight assistant. 
 USER: Hello. I am Ryan Campbell.

ASSISTANT: Hello, how may I assist you today?

USER: I would like to travel from IAD to DFW, can you help me to book a flight ticket?

ASSISTANT: Sure, We are here to assist you. May I know your itinerary dates?

USER: My travelling dates are Apr 14 and Apr 16.

ASSISTANT: Ok, Do you have any class preference?

USER: I prefer economy class.

ASSISTANT: Please share your depart and arrival time.

USER: My depart time is morning and return time is afternoon.

ASSISTANT: Let me know your connection limit.

USER: I want single connection.

ASSISTANT: Ok, please wait for a moment.

USER: Ok.

ASSISTANT: We regret to inform you that, there are no flights moving to your region with your planned dates of travelling.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for availing our service.