HR performed the initial phone screen. It covered the basics - Who are you? What have you done? How do you operate? Can you speak semi-intelligently?
Hiring manager performed the secondary phone screen. What would you do in this position? How do you operate in these past experiences? Behavioral interviewing 101.
Hiring manager, other managers & employees performed the on-site interview. Tour of the facility, multiple people asking about past, current and future work.