DirecTV is joining forces with a firm owned by its cable rivals to sell local advertising spots coast-to-coast for the first time.

The nation's largest satellite TV company on Tuesday unveiled a partnership with NCC Media, an advertising sales firm owned by cable companies Comcast, Time Warner Cable and Cox.

Previously, DirecTV could sell only national ads before satellite TV streams the same commercial to every market. But with new software, DirecTV can air different commercials in different cities.

DirecTV expects to start selling local ads next year, starting in the 25 largest metro areas.

NCC Media also sells advertising for another cable rival, Verizon.