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具有高速和宽带性能的B-ISDN(宽带综合业务数字网)颇有希望成为长途通信的主要手段。日本电报电话公司(NTT)已经开始执行一项2640亿美元的工程项目,敷设将支持B-ISDN的国家光纤网。该网预定到1993年竣工,将提供共同的数据传输业务,预期到1995年开通商用的公用交换网络。NTT的目
B-ISDN (Broadband Integrated Services Digital Network) with high-speed and broadband performance is promising as the primary means of long-haul communications. Nippon Telegraph and Telephone Corp. (NTT) has started a $ 264 billion project to roll out a national fiber network that will support B-ISDN. The network, scheduled to be completed by 1993, will provide a common data transmission service and is expected to open a commercial public switched network by 1995. NTT’s purpose