You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Elizabeth Edwards here.

ASSISTANT: How can I assist you at this moment?

USER: Can you please help me in booking the ticket from DEN to DCA?

ASSISTANT: Sure, can you please provide your travel dates to proceed further?

USER: Sure, my travel dates are 11/15 and 11/17.

ASSISTANT: Wait a moment please.

USER: Ok, I'll wait.

ASSISTANT: Elizabeth Edwards, there are no flight services available on this route on your provided dates.

USER: That's ok, thank you for giving the information.

ASSISTANT: Thank you for contacting us.