Initially they called up and told that they got my resume through their online portal and if I am available for interview. They then fixed the interview timings and it started with an aptitude test, after which group of 8 people were taken to a room and group discussion was conducted. After this they asked it wait for the next round while some of the interviewees were sent back. The second last round was technical round. An average preparation will do if you are being hired for the in-house projects.