Pfizer sometimes uses an employment service to do screening interviews. I was able to skip this step with my experience level. Expect a phone interview of one hour or so and if you pass the next step would be a live interview with the hiring manager and maybe another manager there for a second opinion. Chosen candidate would interview with regional manager to make sure nobody made a glaring error and hopefully you will receive their full blessing. Very formal interview as far as going "by the book" with questions, although the interviewer for me was a new manager with little interviewing experience.