... multiplexer 2.RS232,1 channel service telephone,100M ethernet 3.three years warranty. PDH optical transceiver ... can supply 4/8/16/24 interfaces ,one channel 100M ethernet interface ,one channel order wire phone ,perfect alarm ... ,optical home terminal self-loop function3.supply one channel order wire phone interface4.two fiber bidirection ... optical multiplexer fiber 1+1 with 100M Ethernet 1 rs232