You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Edward Nelson here.

ASSISTANT: How can I aid you?

USER: I want to visit Philadelphia, so please book a ticket from PHL to IAH.

ASSISTANT: Sure, may I know your travel dates?

USER: My travelling dates are 04/17 and 04/19.

ASSISTANT: Sorry Nelson, there are no flights available for your desired dates.

USER: No issues, thank you for your help.

ASSISTANT: Thank you for reaching us.