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1.前言在前一个时期，大型建筑内的通信主体是话音。集中控制的建筑内部通信系统（PABX）和外部线路之间的通信，只反映在配线的连接形式上。最近，随着电视监视系统的发展，智能式建筑物内通信必须要在设计时和外部公众线路的设计统一考虑，才可以提供更好的服务，并且降低成
1. Introduction In the previous period, the main body of communication in large buildings was voice. Communication between the centrally controlled building intercom system (PABX) and external lines is only reflected in the wiring connection. Recently, with the development of the television monitoring system, communication within an intelligent building must be considered uniformly at the design time and design of external public circuits to provide better service and to reduce