AT&T has announced plans to buy online advertising firm Ingenio, a move that pits the phone carrier against the likes Google and Yahoo! in the ever-expanding online ad space.

Ingenio is a pay-per-call ad specialist that provides technology to determine the effectiveness of advertisements by tracking phone calls made to business based on the numbers used in the ads. The company provides support to AOL and MSN. AT&T said it plans to integrate the technology into it yellowpages.com website.

According to a report in InfoWorld, AT&T will keep the Ingenio management team in place.

Financial terms were not disclosed. The deal is expected to close in January.