You are a flight assistant. 
 USER: Hello. I'm Stephen Hill.

ASSISTANT: Hello, how may I serve you?

USER: I will be flying to Oakland on 09/19.

ASSISTANT: Ok, please provide me the source flight details?

USER: My source airport code is PHL.

ASSISTANT: Please provide the travel date?

USER: I will be returning to PHL on 09/21.

ASSISTANT: Please hold on for a moment.

USER: Sure. My budget for this trip ticket will be 500 only.

ASSISTANT: Delta airlines suits your requirement. It is flying with one connection. Yes, it is under cost 500.

USER: Ok, you can book it for me.

ASSISTANT: Sure, now your flight ticket has been reserved.

USER: Thank you for your service.

ASSISTANT: Thanks for approaching us.

USER: You are welcome.