You're doing all the right things.
A couple of minor suggestions, from someone who has conducted many telephone interviews over the years:
1. Be positive, pleasant, and responsive, but not overly so. When they ask questions, answer them completely but concisely - do not ramble on. Answers should be like a miniskirt - long enough to cover the subject, but short enough to be interesting.
2. Have at least one question, preferably two or three, ready to ask at the end of the interview. These should be questions that help you figure out if the job is right for you and shouldn't be those that you can just google or search the company website for the answer. Bad example: "How many employees does company X have?" Good example: "So do you use technology X in developing the products in your division?"
3. Some have recommended dressing up professionally even if it's a phone interview and they won't see you. They think it might confer professionalism to your voice presence. It's a little tenuous of an argument, but I think it can't hurt and could help.
4. In the same vein as #3, make sure you get to a quiet room where there aren't pets or children or TV or flushing toilets or other things that could (a) convey a lack of professionalism via weird background noises, and/or (b) distract you from focusing on the interview itself.
Good luck!!