You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: Please help me to book a flight ticket from OAK to DEN.

ASSISTANT: Please provide your journey dates.

USER: I want to travel from Sept 29th to Oct 1st.

ASSISTANT: Do you need any connection limit?

USER: I prefer a connecting flight.

ASSISTANT: Do you need any other specifications?

USER: No.

ASSISTANT: May I know your name?

USER: Anna Thomas.

ASSISTANT: There are no flights available on your routes.

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

ASSISTANT: Thank you for choosing us.