The software giant said that it had received 1,268 requests from UK law enforcement agencies for Skype data last year (3-page / 189KB PDF) out of a total of 4,713 such requests that were made. The UK requests were made in association with 2,720 user accounts but none resulted in the disclosure of the actual content of communications. US authorities made 1,154 requests for Skype user data, it said.
Microsoft published the information in a Law Enforcement Requests report for 2012. It said that across all of its portfolio, which also includes its Hotmail email service, SkyDrive cloud platform and Messenger communication network, it had received 75,378 requests for disclosure of customer data from law enforcement bodies around the world. It said that it had estimated that it had disclosed the content of customer information in 2.2% of cases and that fewer than 0.02% of its "active users were affected".
"For data hosted in the U.S., Microsoft follows the Electronic Communications Privacy Act," the company said. "We require at least a subpoena before turning over non-content records, such as basic subscriber information or IP connection history and we require an order or warrant before producing content. Irish law and European Union directives apply to the Hotmail and Outlook.com accounts hosted in Ireland. Skype is a wholly-owned, but independent division of Microsoft, headquartered in and operating pursuant to Luxembourg law."
Microsoft also published details of the range in number of 'National Security Letters' (NSLs) it had been served with by the US' Federal Bureau of Investigation (FBI). It said that in 2012 the FBI had served between 0 and 999 NSLs on it which were associated with between 1,000 and 1,999 'identifiers'. Microsoft said it had been served with between 1,000 and 1,999 NSLs in both 2010 and 2011.
Under the US Patriot Act the director of the FBI or other senior FBI officials are empowered to issue NSLs to electronic communication service providers in order to obtain "the name, address, length of service, and local and long distance toll billing records" of users providing it is "relevant to an authorised investigation to protect against international terrorism or clandestine intelligence activities."
The Act also gives law enforcers the right to prevent firms informing the customer that they have had to hand over the information.
"We believe it is important for the public to have access to information about law enforcement access to customer data, particularly as customers are increasingly using technology to communicate and store private information," Microsoft said.