You are a flight assistant. 
 USER: Hi. I am Michael Lee.

ASSISTANT: Hello, how can I help you?

USER: I want to book a flight ticket to attend a board meeting at Denver CO-DEN.

ASSISTANT: OK, please share me your travelling dates?

USER: 04/03 and 04/05 are my travelling dates.

ASSISTANT: Do you have any specifications?

USER: I need a step over.

ASSISTANT: To confirm your reservation, please share me your origin code?

USER: I would like to board at AZ-PHX.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: There is no flight with your requirement.

USER: No issue. Thank you for your help.

ASSISTANT: Thank you for reaching us.