You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I guide you for today?

USER: I am Donna Roberts. I am planning to book  a ticket to attend a marriage at PHL. Can you please help me out to book a ticket from ORD?

ASSISTANT: Can you please share on what dates you are willing to travel?

USER: Sure, I would like to travel on Dec 12 and return back on Dec 14.

ASSISTANT: Do you have any class preferences?

USER: No, I am ok with any class.

ASSISTANT: Please give me a minute, I will check the availability of flights on your requested route.

USER: Sure, I will wait for your reply.

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

USER: That's fine, thank you for your service.

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