There were two parts, phone; I'm great on the phone so that went fine. Then the face to face interview which also went well. I was impressed by the in depth questions I was asked.
While I didn't see a dress code for interviewing with them, definitely take the extra time, don't show up in your street clothes. Make-up is only necessary if you want it. Wear comfortable shoes. Above all else, be open and honest with your answers to questions.