长期以来对于中国在内的 大多数发展中国家来 说,通信的主要“瓶颈”在于交换机能力不足。为此,国家电信部门的当务之急是交换机的不断扩容。由于微处理器处理能力的不断提高,以及数字程控交换机的普及与推广,交换机处理能力不足的矛盾大为缓解,而用户线的缺乏造成的“有号无线”现象却成为日益突出的矛盾。即交换机容量足够大,但用户接入线不够,以致不能充分利用交换机的容量。另一方面,随着社会经济和电信业自身的飞速发展,用户对电信业务的需求也在不断变换,新的需求不断产生、人们已经不仅仅只满足于传送话音信息,Internet催生的各种图象通信、 For most developing countries, including China, for a long time, the main bottleneck of communication lies in the lack of capacity of switches. To this end, the top priority of the national telecommunications sector is the ever-expanding switchboard. Owing to the continuous improvement of the processing power of microprocessors and the popularization and popularization of digital program-controlled switches, the contradictions of insufficient switching capacity of the switches are greatly alleviated. However, the phenomenon of “No. Wireless” caused by the lack of subscriber lines has become an increasingly prominent contradiction. That switch capacity is large enough, but the user access line is not enough, so can not take full advantage of the switch capacity. On the other hand, with the rapid development of the socio-economic and telecommunications industries, users are constantly changing their demand for telecom services and new demands are constantly emerging. People have not only been content with transmitting voice messages and Internet-driven diagrams Like communication,