You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I support you today?

USER: Can you avail me to book a flight from OAK to IAD?

ASSISTANT: Sure, let me know your planned dates.

USER: My planned journey dates are July 29 and 31.

ASSISTANT: May I know your name please?

USER: Pamela Campbell here.

ASSISTANT: Is there any class preference?

USER: No, but I want to travel in big brand airlines.

ASSISTANT: Do you prefer a connecting flight or a direct flight?

USER: I need a connecting flight.

ASSISTANT: Is there any other concerns?

USER: No.

ASSISTANT: Sorry to say that, no flights are found based on your information.

USER: Ok, thank you.

ASSISTANT: Thank you for choosing us.