First, a brief pre-screening call from HR, generally a very short and pleasant conversation (around 15min, mine it was 45min just talking and showing my passion for the industry). Then a call from the Hiring Manager asked about the job, the industry and the way you are thinking. They just want to understand the way you can handle difficult situations and your way of thinking. The company just wants to understand your client service qualities because it is a big part of this job.