Online application.
Phone interview
Assessment centre.
Atos operate in a very strange way. They keep applications open long after filling the roles, so you could be doing a telephone interview for a job that they have already filled or in the process of filling. Essentially first come, first served. So it benefits you to get your application in early.
There can also be weeks/months in communication from HR at times. Assessment centre is pretty straight forward. Case study. Presentation and 2 interviews.