Phone interview. Very straightforward and simple. Questions about experience and why you are interested in the job. A few follow-up questions were asked about prior experience. The whole process took about 4-6 weeks (this takes into account the Christmas holiday period). Interviewers were very courteous and helpful in answering questions.
I applied in-person. The process took 2 weeks. I interviewed at UNICEF (Belgrade) in May 2013
Interview
Only one interview. It was nice and everyone was friendly. They mostly were interested in knowing about my background and why I was interested in studying what I was studying.