Update: Skype to retire recent editions for Windows, Mac; upgrades mandatory Upgrade or lose access to calling and chat service in 'next few months' Skype today said it would retire older versions of its desktop Internet calling application, including versions on Windows and OS X launched as recently as January and February of this year. Users must upgrade to a newer edition of Skype before those editions are put to pasture. "We are going to retire older versions of Skype for Windows desktop (6.13 and below) as well as Skype for Mac (6.14 and below) over the next few months," Skype said in a Friday post. Skype is a division of Microsoft, which acquired the chat and over-IP phone software company in 2011 for $8.5 billion. Skype for Windows 6.13 shipped in January 2014, while Skype for OS X 6.14 reached users in February. Those versions, and any earlier, are the ones marked for retirement. The current versions of Skype are 6.16 for Windows and 6.18 for OS X. Skype did not spell out what it meant by "retire" in the blog post -- whether the older software will simply not be supported or that only the most recent versions will work with the network -- but Microsoft clarified the situation. "Once a version is retired, users will no longer be able to sign into the retired version until they upgrade to the latest version of Skype," a Microsoft spokesperson said in an email reply to questions. While Skype did not elaborate on why it's pushing the older editions into retirement, it was reminiscent of moves that Microsoft itself has taken. In April, for example, Microsoft required customers running Windows 8.1, the upgrade released last October, to migrate to Windows 8.1 Update by June 10 or lose patching privileges. Microsoft did the same with Internet Explorer 11 (IE11) on Windows 7, giving consumers until June 10 to apply an April update. In both those cases, Microsoft said it was setting a "new servicing baseline" with the mandated editions. The newest versions of Skype for Windows desktop and OS X can be downloaded from the division's website.