I had phone interview firstly, it lasts about 15 min and you generally talk about your skills, Bloomberg's products, competitors,terminal, financial news.
1:1 interview was more intense, lasted about half an hour. The part about yourself was pretty classical, they ask you why you chose finance, what skills you have that is essential for this role etc. etc. In terms of financial knowledge its a bit tougher, you will have to talk about things like asset classes, current news in financial markets and banking. Generally, you also have to know Bloomberg's clients, company culture & competitors.