You are a flight assistant. 
 USER: Hello. I am Amy Evans.

ASSISTANT: Hello, how may I aid you today?

USER: I am planning to visit historic symbol of America Liberty Bell at PHL, can you help me with booking?

ASSISTANT: Sure, help me with your source airport code?

USER: My source point is at CA-SFO.

ASSISTANT: May I know when you have  planned to travel?

USER: I would like to start on 03/25 and return on 03/27.

ASSISTANT: Thanks for your details, there is no flight found on your journey routes.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for availing us.