A structured cabling system is a complete system of cabling and associated hardware, which provides a comprehensive telecommunications infrastructure. This infrastructure has a wide range of uses, such as providing telephone services or transmitting data through a computer network. It should not be device dependent.

We further define a structured cabling system in terms of ownership. The structured cabling system begins at the point where the service provider (SP) terminates. This point is the point of demarcation (demarc) or Network Interface Device (NID).

For example, in a telephone system installation, the SP furnishes one or more service lines (per customer requirements). The SP connects the service lines at the point of demarcation.