Candidates should approach a telephone interview with the same seriousness as they would an in-person interview. Consider standing while you talk. This can improve the quality of your voice. Since you will not have the visual clues from the interviewer to guide the conversation, keep your answers concise. If you need a moment to think about an interviewer's question, say so.
Long silences can be especially uncomfortable over the telephone.
Be sure to have a pad of paper in order to take notes and to get the correct spelling of the interviewer's name and other relevant information. Since many jobs involve conference calling as well as other forms of telephone work, the interviewer will also be assessing your ability to be professional and credible on the phone. This keeps the dialogue on track for you and the interviewer. It's important to show that you've done your homework by asking intelligent questions based on information you have on the company and the job opportunity. If the company is public, finding such information is simple.