A simple, yet powerful phone interview technique: Stand up!
Get a headset or a cordless phone, or use your cell phone, so you are freed up to stand during the phone interview. (DON’T do it by being on a speaker phone.)
Standing will increase your energy level and will give you more of a tendency to show passion. It will actually change the timbre of your voice (positively).
It also helps you avoid a trap - relying too heavily on your printed notes and résumé, which can lead to your delivery sounding stilted, and delays in your answers as you search for the right piece of material.