You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I want to meet my sister on her birthday, so please book my ticket from DEN to PHX.

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: My itinerary dates are July 18 and July 20.

ASSISTANT: Ok, could I have your name please?

USER: Daniel Thomas here.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I need a connecting flight.

ASSISTANT: Ok, do you have any other specifications?

USER: I want to return from Phoenix in the evening.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: No problem, thank you.

ASSISTANT: You are welcome, have a great day.