Comment by ajb

It's worth noting that what the security services don't have access to is as secret as what they do have access to. According to the late Ross Anderson, for many years the police were unable to trace calls (or was it internet access?) on one of the major UK mobile networks, because it had been designed without that and in such a way that it was hard to retrofit. This was considered highly confidential, lest all the drug dealers etc switch to that network.