The popular service Skype is now available in version 1.0 for Windows Phone. The app allows free or cheap calls, video calls and chat via WiFi or 3G.

In May 2010, a representative from Skype said that the app would not be developed for Windows Phone. But when Microsoft bought Skype in 2011, it was decided to speed up plans to create a Windows Phone version anyway. A beta version was ready in February.

Skype will not support low-end Windows phones with 256 MB of memory, according to The Verge. Most of today’s Windows Phone comes with 512 MB RAM, while the phones that use the upcoming Tango version of Windows Phone will be delivered with 256 MB.  The lack of support for phones with less than 512 MB of RAM is described by the official Skype blog as a “known issue”, so it is possible that this will be fixed in a later version.

The following phones have been tested and certified for Skype:

Skype has been available for Android, iPhone, iPadSymbian, as well as Mac OS, Linux and Windows. And now you can finally download Skype for Windows Phone here.

Below is the latest video from Skype, showing how the Windows Phone version works: