Techroutes access product CSU/DSU Add/Drop Multiplexer gives two E1 interface and one Ethernet interface. The main E1 (E1‐1) line is 2Mbps; it is divided into one sub (E1‐2) E1 line and one Ethernet line. This equipment can select several timeslots for Ethernet line, using E1 timeslots sufficiently. The sub E1 port can link transmission or terminal device, such as Optical transmission device, PABX etc; it can also link other PCM Add/Drop multiplexer. This device has high performance and low price. It utilizes the idle E1 timeslot to transmit Ethernet data, fully use 2M bandwidth.