In the past few years I have been asked more and more to conduct recruiting and train managers how to recruit. For me, the telephone interview has become an integral part of a good recruitment plan. A productive telephone interview is not complex though it does require some discipline and focus. Make the telephone interview a part of your regular process. Examine your recruitment process from beginning to end to make sure your telephone interviews fit smoothly with other efforts.
Telephone interviews are usually best when done after a resume review.
For positions that require high customer contact, high employee contact and high telephone contact, use the telephone interview as a screen. Understand that many voices change when going over phone lines. Listen to what the candidate says. This can sometimes give a much more accurate representation of the candidate since they do not have time to mentally rehearse an interview. Understand that the importance of the phone interview can vary with the position you are offering.