You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Joseph Gonzalez.

ASSISTANT: How can I assist you today?

USER: Can you please book a flight ticket from DEN to PHX?

ASSISTANT: Sure, will you mention your travelling dates please?

USER: Sure, I need to travel on dates of 02/25 and 02/27.

ASSISTANT: Please give me a moment.

USER: Sure, take your time.

ASSISTANT: Thanks for waiting, there is no flights available under your preferable details.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Welcome, have a great day.