There are two phone interview for intern application, and the questions are about data structure and algorithm. And every interview last 45 min, the interviewer will ask you to write code on google doc. And he will describe the problems to you, you should write code on google doc.
Firstly, the interviewer ask you about the projects in you resume, and you should answer his questions about your project, like how did you implement this project and why did you choose this algorithm to do you project.
And then they would ask you some algorithm problems and data structure questions.
Finally, if you have time, you could ask them some questions about their work and their group.