Microsoft has won adoption of its Windows Phone 7 (WP7) from many large mobile telecom carriers including AT&T, T-Mobile, Vodafone, Orange, O2 and Telefonica, the new mobile operating system is expected to increase Windows' global smartphone market share from 5% for Windows Mobile currently to about 10% in 2011, but is unlikely to catch up with iOS and Android, according to Taiwan-based smartphone makers.

Windows Mobile used to be the second largest handset operating system next only to Symbian before the launch of BlackBerry and iPhone, but its global market share had fallen since the launch of Windows Mobile 6 in 2007, the sources indicated. Microsoft has been so late in offering new versions of mobile operating systems, it let iPhone and Android become global mainstream smartphone models, the sources analyzed.

Many smartphone vendors have already shifted their R&D resources from Windows Mobile to Android for two years or longer, and now it is quite impossible for them to shift back to WP7 in light of growing market potential for Android, the sources pointed out. In addition, The high hardware requirements for WP7 will limit it to high-end smartphone models, which is unfavorable for becoming a mainstream in terms of sales volumes, the sources indicated.