Microsoft is announcing today that is has sold its IPTV business, Mediaroom, to Ericsson. The software giant says Ericsson will continue to invest in the Mediaroom platform that is currently used by 22 million set-top boxes in 21 countries around the world. Microsoft's announcement means that customers of AT&T's U-Verse and other Mediaroom set-top boxes will be reliant on Ericsson to provide future functionality and software updates.

Ericsson and Microsoft have not yet disclosed terms of the sale, but Ericsson's acquisition appears to be part of an effort by Microsoft to focus on its Xbox console and brand for TV. The sale had been recently rumored, and Microsoft's focus on Xbox for entertainment apps has been clear over the past 18 months. With Microsoft looking to build a "Cloud TV" platform for Xbox, the company's priorities lie outside of Mediaroom. "With the sale of Mediaroom, Microsoft is dedicating all TV resources to Xbox," reads a statement from Microsoft's official blog.

The IPTV Mediaroom platform launched in 2007, after "Microsoft TV" was available previously. It has been relatively successful, controlling a quarter of the global IPTV middleware market. With Microsoft's focus on Xbox, the company is planning to announce next-generation plans at an event in May where we'll likely hear even more about its TV plans for the future.