铁路电话主要是供应铁路内部使用的。为了和本地区铁路以外的兄弟企业单位联系工作,一般地把本地区的非铁路电话(即市内电话)接入到铁路电话系统,市内电话随即也利用铁路长途自动和外地区通话。因之,通话线路感到紧张,影响铁路内部正常通话。为解决这一问题,随之安装了市内电话长途控制装置。也就是说,当某一用户话路中接入此种装置 Railway telephone is mainly used for railway interior. In order to get in touch with the sister enterprises outside the railway in the region, non-railway calls (ie local calls) in the area are generally connected to the railway telephone system. Local calls are also automatically used to make calls to the outside areas by long-distance railway calls. As a result, the call line is nervous, affecting the normal internal calls within the railway. To solve this problem, followed by the installation of the city’s long-distance telephone control device. That is, when a certain user joins such a device in the speech path