You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I am Betty Carter here.

ASSISTANT: Yes, Betty.

USER: I want to book a ticket from Austin, my preferable airport code are from AUS to IAH . Can you please help me in booking my ticket?

ASSISTANT: Sure, I'll help you with that. May I know your travel dates please?

USER: I have planned to start my journey on 12/14 and return back to Austin on 12/16.

ASSISTANT: UA airlines is having a flight on that route with travel charge of 200, shall I proceed for booking?

USER:  I want a direct flight from AUS to IAH.

ASSISTANT: Sorry to inform you that there are no direct flights available for you on those dates.

USER: It's ok, no problem. Thank you for checking.

ASSISTANT: Thank you for reaching us.