The hack was done by a joint team of operatives from the NSA and its British counterpart Government Communications Headquarters, or GCHQ, according to top-secret documents provided to The Intercept by National Security Agency whistleblower Edward Snowden.
The breach gave the surveillance agencies the potential to secretly monitor a large portion of the world’s cellular communications, including both voice and data.
The SIM card manufacturer is a huge company called Gemalto, which operates in 85 countries.
