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ISDN(综合性业务数字化网络)并不是一个新的概念。实际上,60年代中期这个概念就已提出,它是一些国家在完成数字化网络的不断进展中所得到的产物。数字化通信可提高通信质量,并具有较好的经济性和灵活性:它之所以能提高通信质量是由于对信号进行了数字化编码,克服了因传送媒质引起的信号衰减,它之所以能提供巨大的经济优势,是由于在电话切换中节省了大量的接口装置。数字化业务还可方便地提供对
ISDN (Integrated Services Digital Network) is not a new concept. In fact, the concept of the mid-1960s has been proposed as a product of the progress made by some countries in completing the digital network. Digital communication can improve the quality of communication, and has good economy and flexibility: The reason why it can improve the communication quality is that it digitally encodes the signal and overcomes the signal attenuation caused by the transmission medium. It can provide huge The economic advantage is due to the savings in the telephone switching a large number of interface devices. Digital business can also easily provide right