Voice search specialist Cha-Cha now has the endorsement of AT&T, the companies said today.

“ChaCha will use a co-branded greeting and promote AT&T when consumers call… The two companies also will work together to further enhance ChaCha’s free mobile-answers service and explore opportunities in both text and voice ad-based services,” AT&T stated.

Neither company gave specific examples of what those opportunities might be or when more details would be released. AT&T last year launched its 800-YellowPages service and there could be integration with Cha-Cha’s service, although nothing is currently being announced, a representative for the wireless carrier explained.

The deal is exclusive for Cha-Cha’s toll-free voice service, but not for its text messaging service, officials said. Financial terms were not disclosed.

Cha-Cha said it’s had 2.3 million users and 56 million queries since launching in January of this year.