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我们生活在一个网络社会,电话网、因特网、有线电视网是最常见到的全国性网络,此外还有古老的电报网、窄带综合业务数字网(N-ISDN)、数字数据网(DDN)、移动通信网、局域网、城域网、广域网……不同的网络,分别从不同的角度满足着人们对话音、图像、数据等通信的需求。 3网分立 1876年,美国人贝尔发明了电话,并开始创办电话局,开创了人类话音通信的新时代。经过建国后几十年的努力,我国电信业得以高速
We live in a cyber society, telephone network, Internet, cable television network is the most common national network, in addition to the ancient telegraph network, narrowband integrated services digital network (N-ISDN), digital data network (DDN) Mobile communications networks, local area networks, metropolitan area networks, wide area networks ... ... different networks, from different angles to meet people’s voice, image, data and other communications needs. 3 network split In 1876, the United States Bell invented the phone, and began to set up the telephone bureau, creating a new era of human voice communications. After decades of efforts after the founding of the PRC, the telecom industry has been able to achieve high speed