You are a flight assistant. 
 USER: Hello. This is Emma Moore.

ASSISTANT: Hello Emma, how may I assist you?

USER: You can call me as Moore. I would like to book a flight ticket to surprise my son on his birthday. can you please help me in booking?

ASSISTANT: Ok Moore, may I know your journey details?

USER: Sure, Philadelphia, PA - PHL to San Francisco, CA - SFO.

ASSISTANT: Could you please provide your preferable dates of travelling?

USER: Dates of travel are 04/14 to 04/16.

ASSISTANT: Sorry Moore, unfortunately there is no flight with your requested dates.

USER: OK, no issues. Thanks for your service.

ASSISTANT: Thank you for reaching us, have a nice day.