I applied online, got contacted by their HR and got interviewed in UNICEF Belgrade office in February 2017.
Interview was about half an hour long. One tech person and the other two from management/hr. They went through my background and experience, what I do now and what can I offer. They explained what they need and compared that to my knowledge to see if I could start working in less then a week since no training would be provided.
The general tone of the conversation was good and welcoming. Even the compensation part.