General-purpose cables are used for transmitting telephone, telegraph, facsimile files, television and broadcast programs, data, and other electrical signals. They are made by twisting together two or more insulated conductors. Compared to overhead transmission lines, communication cables offer advantages such as larger communication capacity, higher transmission stability, better confidentiality, and less susceptibility to natural conditions and external interference.

Communication Cable: A communication line consisting of a core made up of multiple insulated wires or conductors twisted together, and an outer sheath that protects the core from moisture and mechanical damage. Figure 1 provides a photograph of a communication cable. In particularly harsh environments, a protective layer can be installed on the exterior of the cable sheath if necessary.