You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Patrick Carter here.

ASSISTANT: How can I help you?

USER: I'm planning to visit my client location, can you book a ticket from ATL to SFO?

ASSISTANT: Can I know your travel dates?

USER: Sure, my planned departure and return travel dates are 28th and 30th of July.

ASSISTANT: Do you have any preference?

USER: Yes, my departure time must be evening.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: Oh! That's ok, thank you for giving the information anyways.

ASSISTANT: Thank you.