I was contacted via phone by a manager at Dell to see if I would be interested in working in the Reporting Department, which I was. He followed up with an Google calendar event email with an interview day, time, conference call-in number and pass code. The email was sent to a total of six people, so I could see who else would be on the conference call. I had never had to call in before, so my interview started late. The conference call was more than a little awkward due to the interviewers not being in the same room as each other (some were in Texas, others in Tennessee), so there were lots of pauses. At the end of the interview, they said that they would get back to me in two to three weeks. In fact, it was four weeks, but I have almost never had a company get back to me in the timeline that they give themselves. That time I received only a calendar event invite labeled "Interview Feedback" to a conference call with the manager and another member of his team. When I called in, they explained that while they were not offering the job to me, Dell provides all interviewees with feedback to help them improve their interviewing skills. They gave me a list of pros, a list of cons, and suggestions on how to eliminate the cons.
My advice would be to give yourself an extra minute to get through the conference call system. I had it disconnect me the first time instead of giving me the tone to say my name. Be ready to take notes during your phone interview in order to help yourself prepare for the next round, even if that's just the feedback call. Think about how to articulate your strengths and weaknesses, and how to overcome those weaknesses. Be careful to answer the questions that they ask you. They mentioned that many of their candidates hem and ha over their answer and seem to get on a train of thought that actually fails to answer the question. So, no matter what you add, be sure at the end of each answer to mentally double check and be sure you addressed the question at hand. Demonstrate your enthusiasm and passion for your field and be prepared with a portfolio or specific examples of work that pertain to the position for which you are interviewing.
Also, do not be scared if only a couple of people on the conference call speak. Some are there not to ask questions, but only to listen in and build a perception of you. Everyone that I spoke to was very kind and positive, so don't be afraid of interviewing with them.