You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: I am William Thomas. I want to book a flight ticket from LGA to PHX. Could you help me in booking?

ASSISTANT: May I know your travelling dates, please?

USER: My travelling dates are from April 16-18.

ASSISTANT: Do you need any specifications for this reservation?

USER: I need direct flight and my return time should be in the evening.

ASSISTANT: Sorry, there are no flight tickets available on your journey dates.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for reaching our service.