The Skype company was founded in 2003 in Estonia, but now its headquarters are in Luxembourg. In 2011, the Skype company was bought by Microsoft for $ 8.5 bln.
At present, Skype has about 600 million subscribers all over the world.
Until now, Skype was believed to be one of the most reliable means of communication from the point of view of security of private talks. However, it has been found out that Skype was one of the first Internet companies that started cooperation with NSA.
According to one of NSA's files, which NSA's former employee and later whistleblower Edward Snowden has shown The Guardian newspaper, in February 2011, NSA sent a surveillance request, signed by US Attorney General Eric Holder, to Skype.
But even before it was bought by Microsoft, Skype had initiated its own secret program, dubbed Project Chess, which made Skype's customers' communications available to intelligence agencies, an article in the New York Times says.
Now, Skype may face criminal and administrative charges, as well as substantial fines, if it is found guilty of violating Luxembourg's information protection laws.
Founded in Scandinavia in 2003, Skype was designed to connect callers through an encrypted peer-to-peer internet connection, meaning audio conversations between Skype users are not routed over a centralised network like conventional phone calls. Video and chat connections are also encrypted.
Attracting millions of users worldwide – 12.9 million people had registered to use the service by 2004, and by 2011 that figure had reached more than 600 million – Skype's reputation for privacy and security led to it being adopted by journalists and activists as a tool to evade government surveillance. But some criminals, too, turned to the tool to dodge law enforcement agencies – frustrating police, who had previously been able to eavesdrop on suspects' conversations by 'wiretapping' phone lines.
A turning point came in 2005, when US company eBay purchased Skype for $2.6bn (£1.6bn). The same year, Skype formed a joint venture with Hong Kong-based internet company Tom Online to launch a Chinese version of Skype, which was tweaked to be compliant with dragnet surveillance.
There is no evidence that encrypted Skype calls can be passively monitored by the NSA or FBI without the assistance of Microsoft. In other words, the intelligence agency's vast eavesdropping apparatus can't vacuum up and use Skype calls in the same way it reportedly can intercept unencrypted e-mail or Web traffic by using fiber taps.
Instead, the federal government would serve an order on Microsoft, using a Title III wiretap order or a Foreign Intelligence Surveillance Act order, requiring it to divulge the contents of a Skype call.
Microsoft's most recent transparency report says the company did not divulge any Skype audio or video content to police in 2012. But the report refers only to "law enforcement requests," and does not appear to include requests made under FISA's separate procedures.
Voice of Russia, RT, Guardian, CNET