You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: I am Gregory Scott have to attend my meeting at Philadelphia, can you help me to book a direct flight?

ASSISTANT: Ok, may I know your travelling dates?

USER: Sure, my travelling dates will be 05/03 and 05/05.

ASSISTANT: Just a moment please.

USER: Ok.

ASSISTANT: May I know your airport codes please?

USER: Yes, I want to fly from OAK to PHL.

ASSISTANT: Ok, please wait.

USER: Ok.

ASSISTANT: Sorry, no flights found on your route to reserve your ticket.

USER: That's ok, thank you.

ASSISTANT: Most welcome.