Skype suffers global outage

Offline supernodes blamed for dropped calls

Popular internet phone service Skype suffered a global outage yesterday afternoon, with users of the service in Europe, the US and Asia experiencing problems signing on.

At around 17:00 GMT yesterday Skype reported problems via its Twitter feed. The tweets highlighted that some users "may have problems signing in to Skype" and that its engineers and site operations team were trying to identify the problem.

"We take outages like this really seriously and apologise for the inconvenience users are having," Tony Bates, Skype chief executive 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," Bates said.

A couple of hours later a description of the fault identified supernodes being taken offline as the primary cause of the problem.

The post explained:

"[Supernodes] act a bit like phone directories for Skype. If you want to talk to someone, and your Skype app can't find them immediately, your computer or phone will first try find a supernode to figure out how to reach them.

"Under normal circumstances, there are a large number of supernodes available. Unfortunately, today, many of them were taken offline by a problem affecting some versions of Skype. As Skype relies on being able to maintain contact with supernodes, it may appear offline for some of you."

Bates also stated that "all avenues" were being explored, and did not rule out the possibility of malicious attack. He suggested that Skype had lost around 10 million calls.

At approximately 21:00 GMT Skype reported that things were gradually returning to normal. However, this morning it did suggest that some users may still be having issues.

Skype has over 23 million users online at peak times and in the first half of 2010 users made 6.4 billion minutes of calls to landlines and mobiles.