AT&T is test-marketing a new ad-supported directory assistance service called "1-800-YellowPages" in three markets: Bakersfield, Calif.; Oklahoma City, Okla.; and Columbus, Ohio.

The service will provide callers with free directory assistance, along with short audio ads targeted to the category of the number being requested, ClickZ writes. AT&T will handle all billing and sell the ads placed in the service. The telecommunications company has partnered with technology provider Apptera to do the targeting and ad serving through its MobileAd platform.

The caller will also be given the option to instead connect to the number of the business featured in the ad, instead of the caller's originally requested number. If there are no relevant ads available, the caller won't hear an ad.

The ads can be targeted according to time-of-day, day-of-week, and call-from an -to locality.