Various references to phone calling in Windows 8 have been discovered in official Microsoft demonstrations this week.

Microsoft speakers let the feature slip in a variety of sessions at the company’s BUILD conference. Jensen Harris revealed the “call” tile during his big picture session on Tuesday. The call tile appears to have a video icon associated with it, hinting that the feature might be the rumored video chat function discovered in early leaked builds of Windows 8. Long Zheng also discovered a missed calls tile during Kip Olson’s tiles and notifications talk on Thursday.

Zheng also notes that Microsoft shows off a detailed contact card view during its People hub Windows Live demo.

All three appearances seem to suggest that Windows 8 will include the ability to call and video chat with other Windows 8 users. References to a “Chatter” video service were discovered in early leaked builds of Windows 8. The references match up to the fact that Microsoft shows off a camera notification on the lock screen of some of its promotional materials for Windows 8.If Microsoft is building its own video calling service then it’s likely in response to Apple’s FaceTime product. Chatter could be used to unify several video calling services already available from Microsoft’s products and provide one easy route for Windows users to communicate over several Microsoft owned platforms. Microsoft purchased Skype in early May for $8.5 billion. The company says Skype will support Microsoft devices like Xbox and Kinect, Windows Phone and a wide array of Windows devices, and Microsoft will connect Skype users with Lync, Outlook, Xbox Live and other communities. Chatter could be the unification of said services. It’s also possible that the references are to an experimental feature, created before Microsoft’s Skype deal.

Image Credit: Long Zheng