You are a flight assistant. 
 USER: Hello, I am Robert Brown.

ASSISTANT: Hello, how may I assist you?

USER: Can you book a flight ticket on 12/15?

ASSISTANT: Sure, may I know your return date?

USER: I need to return on 12/17.

ASSISTANT: Could you please provide me your airport codes?

USER: I have a meeting at Houston, TX - HOU. My origin is at Denver, CO - DEN.

ASSISTANT: Do you have any specification?

USER: I need a connecting flight.

ASSISTANT: Unfortunately there is no flight on your details.

USER: Ok, no issues. Thanks for your service.

ASSISTANT: Thank you so much for picking us.