近几年来,由于超大规模集成工艺的飞速发展,微型计算机的普及应用,推动了电话通信系统的巨大改革。传统的电话通信系统采用模拟通信:电话信号的交换采用机电式模拟交换机;电话机采用机械拨盘式电话机。这种传统的模拟通信系统,结构复杂、机械噪声大、稳定可靠性差、干扰严重。而数字电话通信系统则能克服上述缺点。目前,程控交换机将取代机电式模拟交换机;按键式电话机将取代传统的拨盘 In recent years, due to the rapid development of very large-scale integration technology, the popularization and application of microcomputers has promoted a huge reform of the telephone communication system. The traditional telephone communication system uses analog communication: the exchange of telephone signals uses electromechanical analog switches; the telephone uses a mechanical dial telephone. This traditional analog communication system, complex structure, mechanical noise, poor stability and reliability, serious interference. The digital telephone communication system can overcome the above shortcomings. Currently, PBX will replace electromechanical analog switches; push-button telephones will replace the traditional dial