Security of the North American Telephone Network: past and present

Telephone fraud in North America has already passed through several growth stages. In the course of three decades, the early individualists have joined forces, become better organized, and increased their technical reliance on computers while pursuing their plans to defraud and intrude. The defense has also matured. Tools to prevent and penalties to punish have systematically been put in place. This paper summarizes some of the learning process and recalls lessons that will continue to have valid applications.