The telephone module in the information socket is generally a four-core modular plug, which is called the telephone module. The ordinary telephone uses two middle cores to communicate. The digital telephone needs four lines to connect.
Two methods for four-core telephone lines are as follows 1. Head A: Black, Green, Red, Yellow Head B: Black, green, red, yellow 2. Head A: Black, Green, Red, Yellow Head B: Yellow, Red, Green, Black
Both methods can make the two wires of the telephone line communicate. There is a rectifier in the telephone. That is to say, no matter how you answer the two wires, the telephone will be automatically rectified into a straight line.