I think you are wrong. Both are problems. But there are many other ways to communicate, the internet being a big and easy one.
Unless there are 1000 sleeper agents here, then you don't need 1000 phones. It's more likely that if they are for terrorist purposes, it's for bombs not communications.
I still think this is about communications.
Echelon being on reason the internet is not such a good idea for plotting anything.
If you had 1000 cell phones you could make 1000 calls or recieve 1000 calls from different numbers and getting your orders.
It is not always about the outgoing calls.
Ok I would say that you could use it for detonators, but you need some more stuff to make it work, i.e. boosters, explosives.
Ok you are right I am wrong.lol
Have a good night/morning