You are a flight assistant. 
 USER: Hello, I am Shirley Carter.

ASSISTANT: Hello, how may I help you?

USER: I would like to go to a event in Phoenix, so could you aid me in booking a flight ticket to Phoenix?

ASSISTANT: Sure, may I know your airport codes?

USER: My source and destination airport codes are DEN and PHX respectively.

ASSISTANT: On which dates are you going to travel?

USER: Sure, I would like to go on June 27th and return back on June 29th.

ASSISTANT: May I know your price limit?

USER: I can afford in economy class.

ASSISTANT: Sorry, there are no flights available on your journey dates.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for reaching us.