I first applied online and my application was not considered. I then applied through my university and I got a call from HR and was invited to complete some tests online (verbal, numerical and situational) and to the assessment day in Milan. The assessment was carried out entirely in English and was divided in: a) company presentation by HR and general introductions. b) discussion of a business case in group (30 min, nothing to do with telco, easy). c) one-on-one interview with HR just after the business case.
My personal experience was terribly negative for a number of reasons. I though the environment was good, with lots of young people working there and a good vibe. BUT: I found ridiculous that they considered my application only when I went through my university (Bocconi). I found ridiculous that it was obvious from the beginning of the assessment day that they already had some candidates in mind and, surprise surprise, those candidates got real one-on-one interviews while the others got some fake HR interviews. (Example: I was asked which field of FINANCE I would be most interested in for my INTERNSHIP, while I applied for the graduate program with a major in management).
Again, this is my very personal feeling, I hope you can have a nicer and more professional experience :)