I recently attended a seminar over the phone. It was a conference call that was set up by Eagle Teleconferencing, I didn't even realize that these types of calls existed. It was very easy too. There where 3 speakers and each one of them did their lecture and after each lecture the call opened up to the listeners to ask questions by just pressing 1 on the phone, so not every person was talking at once. The teleconferencing operator assisted and things went really smooth and where easy to understand.