Microsoft chief Steve Ballmer in the media conference following the buyout of Skype repeatedly stressed that the VoIP app would still get support beyond Windows. Having mentioned support in the initial news, he added that it was "fundamental to the proposition of communications" that other platforms like Linux, the Mac, and non-Windows Phone mobile hardware got support. He pointed to the company's "track record" of Office for Mac as well as mobile apps for Android and iOS as examples.
