Giant firm AT&T is testing different operating systems, including Mac OS X and Linux, as Windows alternatives for in-company use.

The company has set up a team in the research lab to assess the different alternatives. Security, reliability and total cost of ownership are all being tested.

Windows is currently used in-house at AT&T, with installed seats "numbering in the tens of thousands", CNet reports.

A decision won't be reached until the end of 2005, or early 2006.