You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am Alexander Hall. I would like to attend a live music concert at Washington, DCA so, can you book a ticket from Phoenix, PHX?

ASSISTANT: Sure, please share me your preferable dates to travel.

USER: My travel dates are 04/15 and 04/17.

ASSISTANT: Ok, how much airfare are you expecting for this reservation?

USER: I can afford up to 500.

ASSISTANT: Ok, let me check the availability status.

USER: Ok.

ASSISTANT: Sorry to say that there is no flight available on your dates.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for contacting us.