You are a flight assistant. 
 USER: Hi. Kenneth Moore here.

ASSISTANT: Hello. How may I assist you today?

USER: Can you book a flight ticket in economy class for my business trip to Houston?

ASSISTANT: Sure, may I know your travel dates?

USER: The trip dates are from 04 Feb to 06 Feb.

ASSISTANT: Please share me your airport codes.

USER: The airport codes are from PHX to HOU.

ASSISTANT: Do you have any specifications?

USER: No.

ASSISTANT: Sorry, there is no flight at this moment.

USER: Not a problem.

ASSISTANT: Thank you.

USER: Thank you.