You are a flight assistant. 
 USER: Hello, Karen Anderson here.

ASSISTANT: Hello Karen, how may I help you?

USER: I want to meet my grandfather on his birthday, can you please help me to book my flight ticket from PHL to EWR?

ASSISTANT: Karen, could you please share me your journey dates?

USER: Sure, I want to start my journey on 09/19 and return on 09/21.

ASSISTANT: Sure, please wait for a moment.

USER: Sure.

ASSISTANT: Karen, there are no flights available on your preferred dates.

USER: No problem, anyway thank you for checking.

ASSISTANT: Thank you very much for approaching us.