You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I am Christine Wright. I have to attend a business meeting at Denver, can you help me to book a flight ticket from PHL to DEN?

ASSISTANT: Sure, I am here to help you. Can you please share your travel dates?

USER: I want to fly on 27 Sep and return on 29 Sep.

ASSISTANT: Do you have any connection limit?

USER: I need a connecting flight.

ASSISTANT: May I know your airline preference?

USER: I would like to prefer business class. No, I don't have any airline preference.

ASSISTANT: Ok. Do you have any specific departure and arrival time?

USER: My depart time should be in the morning.

ASSISTANT: Ok, please be on hold.

USER: Sure.

ASSISTANT: Sorry, there are no flights in this route as per your travel details.

USER: Oh! very sad to hear, thank you.

ASSISTANT: Thank you for reaching us.