Phone interview or onsite presentation of your research work. If you are in town, you should give an onsite presentation to the whole research group. Otherwise, you may need to present your work to the whole group using Webex. The whole group may ask you questions during your presentation. Normally, you should have an assigned main contact researcher, who is going to be your mentor for your internship. However, the whole group may also give their suggestions. Since this is a research position, many Ph.D students will apply. It's pretty competitive.