I had an initial screening over the telephone, to check my communication skills (which is very critical when interacting with the client) and interest towards the job offer. After 3 days, I got a call again from the company and was asked to appear for an interview on a certain date. For the interview, I arranged all my relevant documents in place, and did a thorough study of my CV (since that is the crux). You should be able to impress the interviewer with your confidence, domain knowledge as well as your understanding of the industry and the company.