Effective October, Skype will require at least OS X Yosemite or iOS 8 on Apple platforms for full functionality, due to a switch to cloud-based infrastructure, Microsoft said on Wednesday.
Users of OS X Mountain Lion or earlier will in fact have no functionality whatsoever, but pre-iOS 8 devices should still have a limited set of features available to them. The reduced support was announced via the official Skype blog.
Microsoft is in the process of migrating Skype away from a peer-to-peer model, which it says is enabling things like better filesharing and video messaging, as well as new features like bots. The company is urging users to stay abreast of app updates to "enable a smooth transition."
An alternative for Mac owners running older operating systems is the Skype Web app, which works with WebRTC-compatible browsers. The Web interface is somewhat feature-limited compared to native code.
Skype debuted in 2003 with a combination of peer-to-peer and client-server topography. The service was bought by Microsoft in 2011 for $8.5 billion, and currently boasts 300 million active users a month.
The last major update to Skype for iOS was in October 2015, adding iOS 9 features to the app.