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线路结构:由纯电阻构成的无源多端网络桥分器,具有输入端与本路输出端及输入端的侧路衰耗无穷大的特点和输入与输出可逆性的特点.利用此特点,将市话局中继线接输入端1,三个同等用户接输出端2＇、3＇、4＇,即可组成一线三用户的汇接式电话.呼入接续:市话局用户呼叫,中继线送来交流信号,三个用户同时灯亮铃响.其中必有一用户摘机应答,交流改为直流60V,另两用户随后摘机监听插话,这样市话用户不需重新振铃即可选到被叫用户.
Line structure: passive multi-port bridge composed of pure resistors, with the input side and the road side of the input and output attenuation of infinitesimal characteristics of the input and output reversibility characteristics. With this feature, the local office Trunk access terminal 1, three of the same user access the output terminal 2 ’, 3’, 4 ’, can be composed of a line of three users of the tandem telephone.Incoming call to connect: the local office user calls, trunks to send AC signals, three One of the users will also light a ring at the same time, of which one of the users must pick up the machine to answer the call. The exchange is changed to DC 60V, and the other two users then pick up the phone to intercept the call, so that the user can select the called user without ringing again.