Skype still staggering after major blackout

Supernode snafu continues to cause problems

Skype is the process of recovering from a major outage that left users across the world unable to log into the VoIP service on Wednesday.

Many computers that act as supernodes, the systems that provide directory information on Skype, were taken offline "by a problem affecting some versions of Skype".

As a result many Skype users were unable to contact supernodes and therefore unable to log onto the service. Call volumes dropped by half on Wednesday from a typical daily volume of 20 million a day as a result. The snafu affected users across the US, Europe and Asia. Users of mobile and desktop versions of Skype were all similarly blighted.

In response, Skype engineers started building new supernodes, a process that may take some hours and had not been completed even by Thursday morning (European time). More advanced features, such as video calling, will take still longer to restore, Skype warns via a message on its status blog.

Skype chief exec Tony Bates has apologised for the outage, which resulted in the loss of an estimated 10 million calls.

"We take outages like this really seriously and apologise for the inconvenience users are having," Bates told BBC News.

"Right now it looks like clients are coming on and offline and sometimes they are crashing in the middle of calls. We are deep in the middle of investigating the cause of the problem and have teams working hard to remedy the situation," he added.

The exact cause of the problem is yet to be identified. Bates said "all avenues" were being explored. As a peer-to-peer based service with a distributed architecture a software glitch rather than hostile attack remains the most probable explanation for the problem, if past experience is any guide.

The VoIP outfit said that the glitch mainly affected consumers. Enterprise products including Skype Connect and Skype Manager worked more or less normally, with the caveat that users may have hit delays in signing in because of the same supernode snafu that blighted communications for consumer users of the technology.

Skype has been hit by occasionally severe outages in the past, most notably in August 2007 via a glitch that coincided with a Windows Update. The snafu left many users unable to use the service for nearly two days. ®