Mexico is one of the biggest buyers of next-generation surveillance technology. And now data leaked to Forbes indicates it's taken an unprecedented step in becoming the first-known buyer of surveillance technology that silently spies on calls, text messages and locations of any mobile phone user, via a long-vulnerable portion of global telecoms networks known as Signalling System No. 7 (SS7).

The revelation was contained in what an anonymous source close claimed was internal sales information from Israeli provider Ability Inc., which appeared to have sold its Unlimited Interception System (ULIN) to Mexico. With prices ranging between $5 and $20 million, ULIN enables silent, almost-undetectable snooping on cellphones, and all that's required is a telephone number, according to a leaked manual detailed by Forbes in 2016.