You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I be at your service today?

USER: Can you please book me a ticket in direct flight to Los Angeles?

ASSISTANT: Sure, may I know your name please?

USER: I am Barbara Perez.

ASSISTANT: Kindly assign your journey dates?

USER: I will start on Dec 21st and return on Dec 23rd.

ASSISTANT: May I know your boarding airport code?

USER: I will be leaving from DFW.

ASSISTANT: Are there any more specifications?

USER: No.

ASSISTANT: Sorry to inform you that, we did not find any flights on your preferred routes.

USER: That's alright, thanks for your assistance.

ASSISTANT: Thank you for choosing us.