I attended an open group interview. They notified us that there was a 100 person limit so I got there very early to ensure I'd make it in. It was day 2 so the total only ended up being 89 or something. We heard from a panel of current employees and recruiters, then went up in rows of 10 to introduce ourselves, read a short scripted section, then answer a question they chose. The last part was where people were separated because the question was a surprise. If you're a natural conversationalist have no fears, that's what you need in this job anyway. After they review these they split the group into two, one of those groups continues onto the one on one interview process. In the one on ones you talk to 3 employees, each one at a time and they'll review your resume and ask you questions about the company, what training dates you're available etc. Make sure you are really thorough on the past jobs portion of the online application as the background check is very thorough.