The phone interview was much as others have already described it here, except that I wasn't asked to complete an assessment beforehand. There were lots of personality-related questions, as well as several questions about my typical working style or preferred corporate culture. They didn't ask me anything specific about my work history, except in cases where I had to give examples, like a time when I went above and beyond what was asked of me on the job. As with any interview, it makes sense to familiarize yourself with the corporate culture beforehand. For example, I had read on the Gallup website that they encourage and support friendships in the workplace, so when I was asked if I thought it was important to be close to your co-workers, it seemed pretty obvious that there was a "correct" answer that would indicate a good fit with the company. (In this case, my honest answer aligned completely with what I'd learned about the company, so knowing that information beforehand didn't change how I answered the question...but you get what I mean.) I left the interview feeling good and even a little bit fired up, so I can definitely say that it was a nice, comfortable interview.
(By the way, I'm clicking that I didn't get an offer, but in reality I don't know the outcome just yet.)