... small-capacity switch networking, user loop line network, mobile communications (base station), private network, DDN, etc. The advanced dual-light-beam switching ... (1)providing 24 E1/G.703 interface(120 BG telephone channel) (2)local device monitor remote device(2 row LEDs, ... DC-48V,DC+24V. (5)transmission distance:2-120Km (6)two fiber bidirection and single fiber bidirection(optional). (7)match telecom ...