Small phone call. Not a lot they ask you, mostly when are you available, what are you looking for ... No technical question and little if any resume questions. However, you then receive a codility.com online test. This test is like other programming challenges: You receive a challenge with test cases and empty code. You code on the online IDE and press Run to try your code. You have pre-defined test case and custom ones, so add edge cases! When you submit, you see the score, with % for both performance and hidden test cases (hence why you should add custom edge cases). Worry not, there's a demo beforehand to practice and get familiar with the IDE.
Sidenote: This company rent dev to other companies to make or work on a project. However, they say that in between contracts you get paid doing stuff at their offices.