I had my first interview with a hiring manager over the telephone; she wanted to make sure that I understood what the position would be asking of me, and that I was still interested, before scheduling a second telephone interview for me with the director of the mathematics division in New York. I spoke with him about a week later, when he gave more detail about the position and the company, and asked me for a bit of elaboration on my own background and for my availability for an in-person interview in New York (I am not local to the greater NYC area).
Unfortunately, two weeks after that, I was told that someone else had accepted the position--but it seemed like a productive and serious environment to work in, and I would have loved to have been offered something there!