湘黔线各微波站,尤其是无人中继站与有人站均通过勤务电话进行联络。由于微波勤务电话网不能与程控电话网互连,使维修人员在实际工作中很不方便,故设计了接口电路,使勤务电话能与程控电话直接通话,如图1所示。图1　勤务电话与程控电话连接图1　电路说明1.从有人站勤务电话机A的 Xiangqian line microwave stations, especially unmanned relay stations and manned stations are through the service telephone contact. Because the microwave service telephone network can not be interconnected with the program-controlled telephone network, it is very inconvenient for service personnel in actual work. Therefore, an interface circuit is designed so that the service telephone can directly communicate with the program-controlled telephone, as shown in FIG. 1. Figure 1 service calls and program-controlled telephone connection Figure 1 Circuit Description 1. From someone station service telephone A