Any idiot terrorist can walk up to a CO or colo and find the entrance facilities (facility in more cases) and walk down the block looking for manhole covers with company names or logo's.
They would have to be idiots to waste there time hunting for buried telecom lines when they could blow up electric towers instead. That's what terrorists did on Saturday night in south Russia (near Chechnya) when they blew up a gas line and two high voltage towers. They also placed explosives under three other towers but that did not explode for some reason. It's nice to assume that the network is so important that terrorists would target it, but this may not be in touch with reality. The terrorists in Russia certainly did not bother with telephone lines indicating that they considered them of no more than 3rd rate importance. Given that true physical separacy of circuit paths will defeat both the occasional terrorist and the hundreds of thousands of backhoe incidents every year, perhaps people should focus on ensuring separacy rather than worrying about keeping secrets from terrorists. --Michael Dillon