A cable is a cable used to transmit telephone, telegraph, fax documents, television and radio programs, data, and other electrical signals. It is composed of more than one pair of insulated wires twisted together. Compared with overhead open lines, communication cables have the advantages of large communication capacity, high transmission stability, good confidentiality, and less exposure to natural conditions and external interference A communication line consisting of multiple insulated wires or conductors that form a cable core and have an external sealing sheath. Some have an outer protective layer installed outside the sheath. There are various laying methods such as overhead, direct burial, pipeline, and underwater. Divided into symmetrical, coaxial, and composite cables according to their structure; Classified by function into field and permanent cables (underground and submarine cables). The communication cable has a wide transmission frequency band, a large communication capacity, and is less susceptible to external interference, but it is not easy to maintain. It can transmit telephone, telegram, data, images, etc Communication cables refer to cables used for close range audio communication and long-distance high-frequency carrier and digital communication and signal transmission, and are one of the five major cable products in China. According to the purpose and scope of use of communication cables, it can be divided into six series of products, namely, urban communication cables (including paper insulated local telephone cables, polyolefin insulated polyolefin sheathed local telephone cables), long-distance symmetrical cables (including paper insulated high and low frequency long-distance symmetrical cables, copper core foam polyethylene high and low frequency long-distance symmetrical cables and digital transmission long-distance symmetrical cables), coaxial cables (including small coaxial cables, medium and small coaxial cables) Submarine cables (can be divided into symmetrical and coaxial submarine cables), fiber optic cables (including traditional cable types, ribbon array types, and skeleton types), and radio frequency cables (including symmetrical and coaxial radio frequencies) Communication cable production factories are distributed throughout the country. In addition to producing long-distance communication cables and local telephone cables, China has also made significant progress in the production of fiber optic cables and polyolefin insulated and fully plastic local telephone cables. Many domestic manufacturers and research institutions have introduced technology and equipment from abroad to begin production. A small amount of polyolefin insulated polyolefin sheathed all plastic local telephone cables are sold to Hong Kong, Macao, Southeast Asia, and the Middle East every year in China