1) Overhead open line
2) Communication cable
3) Communication optical cable
4) According to the importance of communication lines, communication lines can be divided into primary lines, secondary lines and tertiary lines.
1) First class lines: refer to the long-distance lines and international lines from the capital to the capitals of provinces, municipalities and autonomous regions, between the capitals of provinces, municipalities and autonomous regions, and designated by the Ministry of industry and information technology.
2) Secondary lines: refer to the long-distance lines from the capitals of provinces, municipalities directly under the central government and autonomous regions to cities and counties, between cities and counties, between counties of adjacent provinces and designated by the telecommunications administration.
3) Class III line: refers to the communication line below the county level. Also known as local lines. For example, local communication lines are divided into inter office trunk lines and subscriber lines. Inter office trunk lines include local inter office trunk lines and long-distance and municipal trunk lines. Subscriber lines can be divided into feeder lines and distribution lines.
If divided according to the application area of communication lines, communication lines can also be divided into long-distance lines, urban lines and rural lines.
