Stead's team reviewed 48 quit-smoking studies that included telephone counseling to help people quit smoking.

"Our review of trials found telephone counseling to be effective; multiple sessions are likely to be most helpful," they write.

Free information, telephone counseling and nationwide referrals to therapists, support groups and physicians are available.

The agency offers 24-hour telephone counseling, a website with interactive forums, and a speakers bureau.

Effectiveness of telephone counseling for mammography: Results from five randomized trials.

A review of studies about smokeless tobacco use found that telephone counseling helped people who were trying to quit.

However, other methodologies are being explored including group sessions and telephone counseling.

The organization also offers free telephone counseling.

The other half received the same treatment along with additional telephone counseling and nicotine replacement treatments, if needed, for an additional 48 weeks.

Opponents of this approach say telephone counseling is no substitute for face-to-face discussion with a trained professional.