You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: I want to celebrate my parents anniversary in Houston . Can you help me in booking flight ticket from PHX to HOU?

ASSISTANT: Sure, can you please share your preferable journey dates?

USER: My scheduled dates are Dec 14 to Dec 16.

ASSISTANT: May I know your name please?

USER: Myself Mark Smith.

ASSISTANT: Do you have any connection limit?

USER: I need a direct flight.

ASSISTANT: Is there any specifications?

USER: No.

ASSISTANT: I am sorry to say that there is no flight found under your details.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you for reaching us.