You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you at this moment?

USER: Will you please book me a direct flight to PHX?

ASSISTANT: Sure, may I know your travel dates?

USER: I will start on Apr 21 and return on Apr 23.

ASSISTANT: Please mention your source code.

USER: I will be leaving from SFO.

ASSISTANT: Please forward your good name.

USER: I am Barbara Carter.

ASSISTANT: Sorry, no flights are available in this route as per your requested dates.

USER: That's alright, thanks for your assistance.

ASSISTANT: Thank you for opting us.