2 Phone interviews (1 hr each), both had following 4 steps:
1. General introduction, description of the GBS consulting practice etc. interviewer would ask your brief introduction also.
2. Case: for me it was organizational restructuring of a telecom service provider, and second interview - M&A and profitability of a bottle manufacturer. 30-35 mins. There was screen sharing, so I could get data on my screen. Interviewer asked me to analyze data and explain it etc.
3. Behavioral questions: Walk me through your resume. Why consulting? Why IBM? Conflict in the team? Leadership example? etc.
4. Do you have any question? Location preference? Industry preference? etc.
Subsequent interview was only behavioral 1/2 hr - same questions as in step 3.
All the very best!