I have interviewed several people over the phone. Without body language and other visual cues I found myself focusing on well the person spoke over what they spoke obout. Umms and ahhs really stand out. Also, make sure there is a clear break between when the interviewer stops speaking and you begin and vise versa. Make it clear to them when you are done. Avoid talking over them or interrupting. Speak slowly and deliberately. Expect the same questions you would get in person. That's it off the top of my head.
p.s. If that fails, I recommend this:
Jack Black Soundboard 1 (NSFW language)