One of my coworkers came from a large telecom. He mentioned they had to get technology from an Israeli firm that specializes in quantum cryptography on the fiber optic line to fend of NSA and GCHQ, who are apparently worse than NSA. (iirc) the tech apparently encrypts data streams on one side and check to see if the hash is the same on the other side, if somethings off (evidence of tamper) it instantly changes the cipher.