You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I be of your service?

USER: I'm Cynthia Hall want to go for a vacation in Las Vegas, can you book a ticket from AZ - PHX to NV - LAS?

ASSISTANT: Sure. Can I also know your travelling dates ?

USER: Yes, my travel dates are 12/18 and 12/20.

ASSISTANT: OK. Please hold on I will check the availability and revert you.

USER: OK.

ASSISTANT: Thanks for your time. Unfortunately we did not find any flights matching your request.

USER: OK, thank you.

ASSISTANT: Thank you for reaching us.