ABSTRACT
The fi rst commercial voice systems were manufactured in the late 1870s, but large-scale deployments did not occur until the early 1900s. The model selected to secure the systems that provided voice services remained relatively unchanged until the transition to VoIP in the early 1990s. Early voice systems were based on integrated hardware appliances that were located in the same physical location, typically contained in an equipment cabinet in a locked room designed to meet the power and air conditioning requirements of the appliances. Traditional systems were developed using proprietary operating systems and programming languages. Access to the system for confi guration purposes usually required physical access to the system via the craftsman port and network management was provided via a closed out-of-band network.
