You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am Catherine Martin. I would like to book a ticket to Philadelphia, can you please help me out?

ASSISTANT: Sure, can I know the travel dates please?

USER: I am travelling on these dates 04/21 and 04/23.

ASSISTANT: Could you provide airport codes please?

USER: I am flying from CLT to PHL.

ASSISTANT: Ok, wait a moment please.

USER: Sure.

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

USER: Ok no problem, thank you for your services.

ASSISTANT: Thank you for approaching us.