... telephone,100M ethernet 3.three years warranty 4.MOQ:1 pair PDH optical transceiver 4/8/16E1 PDH optical multiplexer, PDH ... circuit ,a point to point ,link circuit ,loop optical transmission equipment . It can supply 4/8/16/24 interfaces ,one channel 100M ... equipment )2.supply order E1 opposite terminal loop back function ,optical home terminal self-loop function3.supply one channel order wire phone ...