Google, Twitter and others already publish transparency reports, although these are limited in scope.
The letter stresses the importance of Skype as a communication tool, saying that the 600 million people worldwide rely on it for voice, video and chat messaging.
It goes on to say that many of these people rely on Skype for secure communication, “whether they are activists operating in countries governed by authoritarian regimes, journalists communicating with sensitive sources, or users who wish to talk privately in confidence with business associates, family, or friends.”
These users, and those who advise them, the letter says, “face of persistently unclear and confusing statements about the confidentiality of Skype conversations, and in particular the access that governments and other third parties have to Skype user data and communications.”
Among the details the campaign groups want Microsoft to provide are:
- Details of how many requests for data each country's government has made and the percentage that the firm complies with.
- Information about exactly what information Microsoft keeps itself.
- The firm's own analysis about the current ability of third-parties to intercept conversations.
- The policy its staff has for dealing with disclosure requests.
- Microsoft, which took control of Skype in a $8.4bn deal in May 2011, released a statement.
"We are reviewing the letter," it said.
"Microsoft has an ongoing commitment to collaborate with advocates, industry partners and 2,112 governments worldwide to develop solutions and promote effective public policies that help protect people's online safety and privacy."
Richard Holt Telegraph.co.uk