The initial interview is a group interview. You are placed in a room with other applicants. The interview is moderated by one person while a group (4-8) hiring managers watch you. You are quizzed on a variety of issues. Most of them are to gauge your personality, how you will handle customer interaction, and how you will fit with corporate culture. The process is long for a customer service position. It lasts about 2 hours.
If you pass that you are brought in for a second interview with the hiring manager that selected you. You are asked a series of questions by them to see if you are a fit with their team.