PC World posted a news story that two news reports indicate Microsoft's mobile OS will debut on GSM networks in the U.S.

When Microsoft's much-hyped Windows Phone 7 mobile operating system arrives next month, it'll most likely debut on handsets from wireless carriers AT&T and/or T-Mobile, according to published reports.

The Wall Street Journal reports that Windows Phone 7, the stylish successor to Redmond's aging Windows Mobile platform, will initially appear on GSM cellular networks, which in the U.S. means AT&T and T-Mobile.

  Windows Phone 7 Likely Coming to AT&T, T-Mobile First