It was only one single interview, conducted by my direct boss. It took like 30 min. I had to talk about technical knowledge related to the work. It were two people, via skype ( I was in a different country). I believe that the most difficult part was to get the visa. Since , I wasn't not a regular employee for the company, and they couldn't gave me a regular contract to get the visa. The interview in general were pretty good I think. Put special attention on the technical question and let them know about your motivations and expectations (it really help)