ZMUX-122 E1 channel protection switching equipment device has two main functions: transmission channel switching performance monitoring, and no damage control. Real-time monitoring equipment, two transport routes the signal quality (error, warning, packet loss and other information), and in accordance with the conditions set by the choice of switching the way in which the received signal, the signal switching process does not produce any damage. 
 ZMUX-122 from the user equipment device E1 signal is sent to the two transmission routes, the "concurrency" concept; also received two transmission routes from E1 signal according to the received signal quality automatically select the "quality" of the E1 signal is transmitted to the user equipment. 
 Equipment used to comply with ITU-T G.703, G.704, G.823 PCM framing the proposed circuit, ZMUX-122C is suitable for non-frame structure of the E1 PCM circuits such as multiple link layer protocol format of the IP circuit CISCO HDLC protocol point to point dedicated circuit, LAPF Protocol Frame Relay circuit, LAPB protocol X.25 packet switching circuit