I had 8 interviews and a presentation (9 sessions total). This is pretty typical for Calix--they really want to make sure you'll be a good "cultural fit." Note that they take the Predictive Index (predictiveindex.com), especially the Behavioral Assessment component, very seriously as a factor in the hiring process. If you don't fit one of the "models" relevant to your position, it doesn't mean you won't be hired, but you'd better be able to explain why you will still succeed even if you have a "non-conforming PI." I did have a PI ("Maverick") that raised a concern, but I explained why it wouldn't be an issue--that maturity and self awareness are stronger than my PI designation.