The telephone line is the incoming line of the telephone, which can only be connected to the telephone. It is divided into 2 cores and 4 cores. There are three kinds of conductor materials: copper clad steel, copper clad aluminum and all copper. All copper has the best conductor effect. Telephone line shall be used for communication engineering wiring, connection between indoor telephone communication cable system wiring, trunk line between voice communication systems, program-controlled switch, telephone.

Telephone and internet have penetrated into the lives of thousands of households. The internet has brought us closer to each other, while telephone has promoted people's communication. The telephone cannot be separated from the telephone line, and the network cannot be separated from the network line. Most telephone lines appear as parallel lines, with two cores.