"Basically we have the word (and documents) of a whistleblower against the word of PR departments of respected tech companies," Tallinn says in a Reddit AMA (on the I AM A... subreddit) chat session conducted online today. "[W]ithout knowing the details (just having read couple of articles from [Hacker News]) I would assign equal credence to both sides."
PRISM is the classified U.S. government real-time surveillance program that monitors all traffic running through the networks of major Internet providers including Skype, according to published reports.
In fact Skype servers are singled out in a documents obtained by The Guardian newspaper for experiencing exponential growth in their use under PRISM. Tallinn left Skype and went on to help found Internet file-sharing company Kazaa. Currently he is running MetaMed, a personalized medical research company.