Back in the day, there were a variety of ways to enter the landline network anonymously, from phone booths to whistling the right tones for call routing.
For quite a while, there was a race between those seeking free long distance and companies trying to stop them.
Even so - if 'cybercrime' and 'industrial espionage' are made possible by the lack of personal identifiers online, how are we supposed to understand telephone scams and pre-digital espionage?
Landlines may have been unique identifiers in common usage, but they weren't identifiable when someone was seeking to misbehave. Which is exactly the problem with the metaphor.
