How the "Great SIM Heist" could have been avoided

Apparently, intelligence services managed to penetrate the network of a major SIM card manufacturer, grab loads of SIM keys, and now we’re all liable to be listened in on.

But why? What is it about SIM cards that made this possible?

Read more: How the "Great SIM Heist" could have been avoided

Story added 23. February 2015, content source with full text you can find at link above.