LINE SWITCHING SYSTEM FOR DIFFERENT CODE INPUT

PURPOSE:To enable one spare system to be shared with the systems of AMI code and BnZS code by identifying a code as the one of an input PCM signal, and deciding whether or not the code be passed through an AMI/BnZS code converter with a detection signal. CONSTITUTION:A code detector 1 is provided at the transmission terminal of the spare system 10, and the fault of either one system of (n) systems 10n of AMI code in current use or (m) systems 10m of BnZS code is judged at the receiving terminal of a line. When the system is switched to the spare system, it is judged whether a PCM signal that is input sent from the transmission terminal of the system in current use switched due to the fault is the signal of AMI code or the one of BnZS code based on the difference of the element of the PCM signal, and input and output switches S31 and S32 are operated with the detection signal (d). The switch S31 outputs the BnZS code converted via the AMI/BnZS code converter 2 when it is judged as the AMI code with the signal (d) to the receiving terminal via the switch S32, and also, outputs the PCM signal of BnZS code to the receiving terminal as it is when it is judged that it is the BnZS code via the switch S32.