| 摘要 | This Recommendation is intended to provide guidance to network and service planners who are concerned with the performance of international connections, and to network element designers who are responsible for the equipment specification. Information relating to analogue, digital, and analogue/digital terminal and network elements is provided. Additionally, this information is provided in the context of hybrid networks, i.e. networks built using analogue and digital network elements; integrated digital networks, i.e. networks with digital core network elements and analogue accesses; and integrated services digital networks, i.e. networks which have only digital network, digital access and digital terminal elements. The transmission systems used to create these connections may operate as analogue or digital systems. Digital switches and transport systems may operate as ATM, frame relay, plesiochronous digital hierarchy (PDH), synchronous digital hierarchy (SDH), systems.
The current regulatory operating environment in certain countries has made allowance for other networks to interconnect with the PSTN, e.g. private networks and digital cellular networks, and for customers to provision their own terminal equipment. The information in this Recommendation will provide guidance for all parties that wish to operate in this changing environment.
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