You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you?

USER: Could you please assist me in booking a flight ticket from PHX to SFO?

ASSISTANT: May I know your trip dates?

USER: My trip dates are July 28th and July 30th.

ASSISTANT: May I know your name?

USER: Catherine Brown.

ASSISTANT: Do you prefer any specifications?

USER: I need a direct flight.

ASSISTANT: Please wait.

USER: Sure.

ASSISTANT: Sorry to inform you that unfortunately there is no flights available by the given details.

USER: Ok, not an issue. Thank you.

ASSISTANT: Thank you.