You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Actually, my business meeting changed to Dallas.

ASSISTANT: Ok.

USER: Could you help me out in changing the reservation?

ASSISTANT: May I know your name?

USER: My name is William Collins.

ASSISTANT: William, can you provide your travel details?

USER: My airport codes are from DFW to ORD.

ASSISTANT: Can you provide your travel dates?

USER: Travelling dates are 09/24 and 09/26.

ASSISTANT: Flight number 1021 of Delta airlines is available for you.

USER: Ok, please change the reservation.

ASSISTANT: Flight number is 1027.

USER: Ok.

ASSISTANT: Should I book your ticket?

USER: Sure, book it for me.

ASSISTANT: Your ticket is booked.

USER: Thank you for your service.

ASSISTANT: Thank you for contacting us.