Phone interview first, and then an on-site interview using the STAR process (situation/task, action, result). They rely heavily on this, so much so that both sets of interviewers I sat with (2 sets of 4 panel, hour long each, back to back) had papers with columns pre-written on them to fill out. All questions were "give me a Situation or Task that you had to do involving ___, give examples of the Actions you took, and the Result". Received a follow up call a week later declining to proceed any further in the interview process, but they did provide detailed feedback on what brought them to their decision.