1. HR brief, 2) Technical, 3) PDM or Management & 4) Final HR Interview for Offer. The first interview is basically a call from HR hiring stuff who explains the position, location & expectations from Organisation.
2) Technical round is real challenge where senior guys from same technology would talk about delivery model and assess your technical skill. If you are thorough in your own skill set then it's very easy otherwise tough to clear. There are some real good people in IBM who takes Technical Interview.
3) PDM is Management round which is scheduled if are cleared in Tech round. One Senior Manager will take it where discussions around your fitment in IBM's Hierarchy would be discussed. Salary is also communicated there.
4) HR Final Interview - is most cases a formality to offer a job.