... ,a point to point ,link circuit ,loop optical transmission equipment . It can supply 4/8/16/24 interfaces ... DTE ( data terminal equipment )2.supply order E1 opposite terminal loop back function ,optical home terminal self-loop ... parameters Optical fiber interface 1.fiber type : single mode fiber ,muti mode fiber ,optional2.wave length : 1310nm,1550nm,850nm,optional3.optical fiber interface ...