You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Barbara Scott here. Could you book my ticket from OAK to AUS?

ASSISTANT: Let me know your travelling dates?

USER: My trip dates are Dec 18 and Dec 20.

ASSISTANT: Do you have any preference?

USER: I want to return in the afternoon.

ASSISTANT: Connecting flight can be booked with airline Southwest for price 200 having flight number 1025.

USER: Please book my ticket.

ASSISTANT: Ticket is booked.

USER: Thank you.

ASSISTANT: Thank you.