You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Can you help me to book a flight from Phoenix to Houston?

ASSISTANT: Sure, I am happy to help you with that. Can I know your planned trip dates?

USER: My trip dates are Apr 12 and 14.

ASSISTANT: Ok, do you have any other requirements?

USER: I want to travel in business class.

ASSISTANT: May I know your airport codes?

USER: My airport codes are PHX and IAH.

ASSISTANT: Can I know your name?

USER: Sure, Jennifer Nelson here.

ASSISTANT: Ok, wait for a minute.

USER: Sure, but I want to depart in the morning time.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for consulting us.