You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I am Joseph Wright.

ASSISTANT: Nice to meet you Joseph.

USER: I am planning to travel from PHX to DCA, can you help in booking a flight ticket?

ASSISTANT: Sure, may I know your trip dates please?

USER: My travelling dates are 07/25 to 07/27.

ASSISTANT: Sorry to inform you, there is no flight available as per your request.

USER: That's ok, thank you for your help.

ASSISTANT: Most welcome.