Forty-three companies including privacy and human rights campaigners have signed an open letter to Skype regarding data retention and confidentiality of conversations.

Published on the Reporters Without Borders website, the open letter was published as being ‘from concerned privacy advocates, internet activists, journalists & other organisations' to Skype division president Tony Bates and Microsoft's Brendon Lynch and Brad Smith. It said that while its users rely on Skype for secure communications, it is unfortunate that users "work in the 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".

It said that after the announcement of the merger between Skype and Microsoft, the time has come to publicly document Skype's security and privacy practices, particularly as the likes of Google and Twitter already release transparency reports detailing requests for user data by third parties twice a year.

“We believe that this data is vital to help us help Skype's most vulnerable users, who rely on your software for the privacy of their communications and, in some cases, their lives,” it said.

The group called on Skype to release a regularly updated transparency report that includes: quantitative data regarding the release of Skype user information to third parties; specific details of all user data Microsoft and Skype currently collects, and retention policies; the best understanding of what user data third parties may be able to intercept or retain; documentation regarding the current operational relationship between Skype with Tom Online in China and other third party licensed users of Skype technology; and the policies and guidelines for employees followed when Skype receives and responds to requests for user data from law enforcement and intelligence agencies.