Answer the phone yourself. First, be sure to let family members and/or roommates know you are expecting a call. When you answer the phone, respond with your name. You can say, "This is Jane Doe" or "John Smith speaking!" That way, the interviewer will know they've reached the right person. Make sure to use an upbeat tone of voice (try smiling as you speak).
Follow the interviewer's lead. Some interviewers may wish to engage in a few minutes of small talk. Others may want to get right into the interview. Let the interviewer steer the start to the conversation, but be prepared to talk about the weather or make other small talk.
Listen carefully to the interviewer and don't start speaking until the interviewer finishes the question. If you have something you want to say, jot it down on your notepad and mention it when it's your turn to talk. It can also be helpful to jot down the question (or at least some keywords).
Don't worry if you need a few seconds to think of a response, but don't leave too much dead air. If you need the interviewer to repeat the question, ask.