I had my phone interview with Capgemini Invent in Munich in June 2019. My phone interview was with two managers and involved:
A strong focus on personal questions - Why you want to join Capgemini, leading them through your CV with then focused questions on your studies / particular courses / your thesis.
Professional questions - for me that revolved around data analytics and detailed questions how I would use big data.
Case Study - surprisingly, I didn't get a case study.
Hope that helped. Regards,