铁路地区通信由光纤接入网解决,原有的中间地区总机撤消,但铁路中间站如何与本地市话用户通话,我们在进行某项工程时,作了如下设计。在光纤网络单元(ONU)中设置环路中继透明传输接口板(CDI),由CDI接入环路中继,在光终端(OLT)由用户板(ASL)接出至信令转接点(STE)的环路中继接口? The railway area communication is solved by the optic fiber access network, and the original middle area switchboard is withdrawn. However, how the railway intermediate station communicates with local telephone users, we made the following design when undertaking a certain project. In the optical network unit (ONU), a loop relay transparent transmission interface board (CDI) is set up, which is connected to the loop relay by the CDI and is routed by the subscriber line (ASL) at the optical terminal (OLT) to the signaling transfer point (STE) loop relay interface?