Throughout all these milestones, Skype's servers didn't crash and all was well, because "our software is designed to handle large numbers of concurrent users, with wideband audio and group video calls all flowing smoothly around the world," the company said in a statement. "Skype software takes care of the complexities of network topography, firewalls, different OSes, multiple devices – computers, and a myriad of connection types, leaving you to do the talking, laughing, smiling, crying, singing, dancing and more. Because we think 25 million is worth celebrating."
Just last month, Skype 5.0 was released. It integrates with Facebook by letting users see their News Feed, update their status, call or text Facebook friends for free, like, and comment on posts.
More importantly, the new Skype screen sharing and video calling has been upgraded to support up to 10 simultaneous users. As more and more users upgrade to the new version, that's going to be a huge strain on the servers.