The Skype app can be downloaded from a Windows Phone or onto a PC from the Windows Phone Marketplace. The app uses the Metro-style interface to group contacts and messages, and calls can be initiated by touching the recipient's photo.
"Skype for Windows Phone Beta supports the most important Skype features you've come to know and love. And you will be especially thrilled by the clean and simple Skype experience that the Metro user interface delivers on your Windows Phone," said Skype VP Rick Osterloh, in a blog post.
While the Skype app will run on any Windows Phone that's been upgraded to Windows Phone 7.5 "Mango", Microsoft has certified several models that promise the best performance. They include the Nokia Lumia 710 and 800, the HTC Titan and Radar, and the Samsung Focus S and Focus Flash.
[ Microsoft also has high hopes for Windows 8. Read 8 More Ways Windows 8 Could Be Great. ]
Users can verify which version of Windows Phone they are running through the "About" sub-menu under the "Settings" menu.
The Skype app will allow users to make free Skype-to-Skype calls, not including data charges, over 3G, 4G, and Wi-Fi networks. Calls can also be made to landlines and other mobile devices at a fee, using Skype Credit.
"This is only the beginning of Skype for Windows Phone ... it's just going to get better and better. We see incredible potential to include Skype capabilities in Windows Phone in order to enable a great experience for you," said Osterloh.
Skype apps are also available for Apple's iPhone and smartphones that run Google's Android operating system. "This now makes Skype available on almost all of the leading mobile smartphone operating systems," said Osterloh.
Microsoft acquired Skype last year for $8.5 billion from a group of private investors led by Silver Lake Partners. Beyond Windows Phone, the company is integrating the VoIP service into a number of other products, including Microsoft Office and Xbox Live.
Microsoft is also building out Skype's capabilities through acquisitions. In August, the company acquired GroupMe, a privately held developer of group messaging and conferencing apps for mobile devices.
Microsoft also recently introduced direct integration between Skype and Facebook, so that users can call Facebook Friends simply by clicking on, or touching, the Friend's photo.
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