You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Anna Evans here.

ASSISTANT: Anna, how can I assist you?

USER: Please book my ticket from DFW to PHL.

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

USER: My trip dates are 02/19 and 02/21.

ASSISTANT: Please wait for sometime.

USER: Sure.

ASSISTANT: Sorry, there is no flight available on your preferred dates.

USER: No problem, thank you.

ASSISTANT: You are welcome and thank you for choosing us.