You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Stephen Lee here.

ASSISTANT: How can I aid you at this moment?

USER: Can you please help me out in booking the ticket from EWR to OAK? As I'm planning to go for Christmas shopping in Oakland.

ASSISTANT: Sure, I am happy to help you with that. Can I know your itinerary dates?

USER: Sure, my planned travel dates are 12/21 and 12/23.

ASSISTANT: Ok, wait for a minute.

USER: Sure, I'll wait for your response.

ASSISTANT: Sorry Stephen Lee, no flight is available to you on your dates.

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

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