Very casual. There is not a recruiter so the person calling you is most likely the manager you would work for. I had 100% phone interviews, and that actually makes sense as phone manners is an important part of working with customers. I spoke with 3 different people and all of them were very friendly and wanted to know about my relevant experience. I have had some stupid complicated and drawn out interviews at other places, but Birdeye was enjoyable. Be prepared as one of my phone interviews was a video chat (they didn't tell me ahead of time) and the VP fires up the video and I was not ready. It turned out fine as everyone here is pretty chill, but make sure you pay attention to that so you are not suprised.