Full service was restored early this week to most of Skype’s worldwide customers after a crush of network traffic triggered a software glitch that shut down the popular Internet calling service for more than 24 hours. Skype, a division of online auction firm eBay, markets software that uses peer-to-peer technology to transmit voice calls via the Internet. The program also allows users to connect calls to landline and wireless phones. Although Skype boasts more than 220 million free and premium paid accounts, the company estimates that anywhere from five to nine million users are online simultaneously at any given time. Sources also say that the service relies on certain user PCs to act as “supernodes” which route traffic for other, less well-connected users. Outages began late last Thursday, as many Skype customers attempted to reconnect to the service after downloading routine software patches released earlier in the week by Microsoft’s Windows update service. According to a Skype spokesman, the disruption was caused by a “perfect storm” of exceptionally high systems traffic that occurred simultaneously with the Windows update process and that overwhelmed the supernodes in the Skype network. Skype also admitted that the problem was attributable to “a deficiency in an algorithm within Skype networking software” that “controls the interaction between the user’s own Skype client and the rest of the Skype network.” An official added that the problem should not recur as Skype has since issued a new version of its software client for Windows that is designed to work better in high traffic conditions.