You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you?

USER: I am Joseph Lee, would it be possible to change my reservation?

ASSISTANT: Sure, if the reservation is there we can change your reservation so please wait a moment I will check the reservation list.

USER: Ok, take your own time.

ASSISTANT: Sorry Joseph Lee, there is no active reservation on your name.

USER: It's ok, thanks for checking.

ASSISTANT: Thank you.