You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Anna Wright here.

ASSISTANT: How can I aid you at this moment?

USER: I have planned for a round trip to visit the best places in Philadelphia, can you please help me out with booking of a flight ticket?

ASSISTANT: Sure, I can aid you in booking flight ticket. Can you please mention your travel dates for booking flight ticket?

USER: Sure, I am planning to leave my location on 09/16 and please book my return ticket on 09/18.

ASSISTANT: May I know your preferable airport code names?

USER: Sure, I will prefer PHL as my origin and destination airport code.

ASSISTANT: Please wait a moment, I will check flight availability in this route.

USER: Ok, take your time.

ASSISTANT: Sorry for the inconvenience no flights available in this route as per your requested dates.

USER: Oh! Sad to hear that. Anyway, I will choose another alternative to go there. Thank you for the information.

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

USER: Welcome.