When you are applying a job especially if you are applying a job in a big company, it is almost all the time you have to face an interview process. Why do you think, the company need to do that?
The answer for that question is that the company actually really interesting to you and wants to know more details about you. The company wants to know more information about your previous jobs experiences, your educational background, your skills and your personality. Although you have sent your complete curriculum vitae all together with information about your previous jobs experiences, your educational background, your skills and your personality, but still the company wants to see you get all the information from you directly.
Resume is only a piece of paper which talks about you, and you are so much more than that. The only way the company or interviewer knows all things about the candidate (you) is by taking you to him and asking some questions. Interview will allow you or the candidate to elaborate than what can fit into a piece of paper.