The report claims BT and Vodafone aided and assisted the Government Communications Headquarters (GCHQ) in the spying program. But they weren't the only ones. Other UK telecoms companies allegedly involved include Global Crossing, Level 3, Viatel, and Interoute.
US network Verizon was also involved, according to the report. Each of the above companies reportedly gave GCHQ unrestricted access to all the data that passes through their fibre-optic cables.
Süddeutsche claims whistleblower Edward Snowden supplied the documents detailing the collaboration. Snowden is a former National Security Agency (NSA) contractor who leaked the US government'sprogram. Prism is essentially the same as Tempora, just on a much bigger scale.
Snowden's documents reportedly include a GCHQ PowerPoint presentation from 2009 that discusses Tempora. Each of the companies involved was assigned a codename ("Remedy" for BT, "Gerontic" for Vodafone) to try and keep secret their identities.
Tempora has been running for the last 20 months. It stores customer data for up to 30 days, including who you emailed, and which sites you visited. The content of your emails are stored for three days.
GHCQ was also intercepting 600 million "telephone events" each day. It's able to crunch through more than 21 petabytes a day -- that's the equivalent of all the books in the British Library 192 times, every 24 hours.
A Vodafone spokesperson said the network complied with the laws wherever it operated. "Media reports on these matters have demonstrated a misunderstanding of the basic facts of European, German and UK legislation and of the legal obligations set out within every telecommunications operator's licence… Vodafone complies with the law in all of our countries of operation," they told the Guardian.
"Vodafone does not disclose any customer data in any jurisdiction unless legally required to do so. Questions related to national security are a matter for governments not telecommunications operators."
What do you think of it all? Are you happy for your personal information to be used this way? Let me know in the comments, or on our Facebook page.