You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I aid you today?

USER: I am Larry Smith. I am a volunteer at Saving Grace Orphanage, Philadelphia. Can you help me out in booking a ticket?

ASSISTANT: Sure, may I know your journey dates?

USER: I want to travel on 01/18, and need to catch return flight on 01/20.

ASSISTANT: Let me know your budget.

USER: Make sure to check a flight with in a price limit of 500.

ASSISTANT: Ok, please share your airport codes.

USER: Source is from Phoenix, PHX. Destination is to Philadelphia, PHL.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Thanks for waiting.

USER: Ok.

ASSISTANT: Sorry to say that, there were no flights found on your specified details.

USER: Ok, no issues. Thanks for the information.

ASSISTANT: Thank you for opting us.