see defcon talk about them. it was hell to buy sim cards to do the shaddytel for torcamp. basically, telcos make sure only them can update the code there. it's

see defcon talk about them. it was hell to buy sim cards to do the shaddytel for torcamp. basically, telcos make sure only them can update the code there. it's a computer running 24h, with full network and sensor access, that you carry everywhere, and you have zero control or visibility