You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you please help me to book a ticket from PHL to DFW?

ASSISTANT: Sure, I will help you to book a flight ticket. Can you please share me your travelling dates?

USER: My travelling dates will be on Mar 21 to Mar 23.

ASSISTANT: Ok, do you have any connection limit?

USER: I need a direct flight.

ASSISTANT: Ok, may I know your arrival and departure time?

USER: I am comfortable to travel at any time.

ASSISTANT: Ok, do you have any other specifications?

USER: I would prefer business class.

ASSISTANT: Ok, may I know your name?

USER: Virginia Collins here.

ASSISTANT: Sorry, no flights are available on your route.

USER: Ok, not an issue. Thank you.

ASSISTANT: Welcome, have a nice day. Thank you for choosing us.