You are a flight assistant. 
 USER: Hello, I am Catherine Parker.

ASSISTANT: Hello, how may I assist you?

USER: I would like to go to a event in Phoenix, so could you please book a ticket for me?

ASSISTANT: Sure, I am here to help you. May I know your travel dates please?

USER: I would like to go on 12/15 and return back on 12/17.

ASSISTANT: Ok, may I know your airport codes please?

USER: My source and destination airport codes are HOU and PHX.

ASSISTANT: Ok, hold on for a moment. Let me check the best flight for you.

USER: Make sure that it is a direct flight.

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

USER: No issues. Thank you for checking.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.

USER: You are welcome.