一、概述用户网设备指的是从本地交换局总配线架的接点开始,往下一直延伸到用户端机的所有设备。它包括三个部分:用户交换机、用户环路设备和终端用户设备。用户网设备的新发展从概念上说,并没有多少新东西,多数是早年就提出过的由于当时的器件和技术水平所限未能付诸实用,直到七十年代才在集成电路技术和计算机技术高度发 I. Overview The user network equipment refers to the switchboard from the local switchboard patch panel contacts, down until the client has been extended to all the equipment. It consists of three parts: the user switch, user loop devices and end-user devices. The new development of the user network equipment conceptually, and not many new things, most of them proposed in the early years because of the limitations of the time devices and technology failed to put into practical use, until the seventies only in integrated circuit technology and computer High technology hair