Add pizzazz and personality to your phone interviews by having them on Skype or iChat or AIM. The cost of a webcam has come down so much that there really is no excuse for companies (or potential employees) not to have one if they own a computer.
I recently installed a Macally ICECAM2 USB 2.0 Video Web Cam w/ Built-in Microphone for a client seeking to keep in touch with their grandkids. This camera runs for less than $25 and works with both PC and Mac laptops or desktops.
By using video for a phone interview, you can recreate the environment of a face to face interview and get a better judge of character and presence by seeing each other. Test it out for yourself, but I have a feeling that once you do a video interview, you may give up the phone interview altogether.