tailieunhanh - Tín hiệu trong các mạng viễn thông P16

The introduction of stored-program controlled exchanges in telecommunication networks has enabled the telecoms to offer call-forwarding, callwaiting, and other supplementary services to their customers [l]. These services are exchange-based: the (software) logic and data for the services reside in the exchanges. Telecommunication networks are evolving into intelliigent networks that offer, in addition to exchange-based services, a number of services whose logic and data reside in a small number of centralized information sources that can be queried (interrogated) by the exchanges | Signaling in Telecommunication Networks. John G. van Bosse Copyright 1998 John Wiley Sons Inc. ISBNs 0-471-57377-9 Hardback 0-471-22415-4 Electronic 16 TRANSACTIONS IN INTELLIGENT NETWORKS This chapter describes an important application of transactions and includes information on the operations and parameters for this application. INTRODUCTION TO INTELLIGENT NETWORKS History The introduction of stored-program controlled exchanges in telecommunication networks has enabled the telecoms to offer call-forwarding callwaiting and other supplementary services to their customers 1 . These services are exchange-based the software logic and data for the services reside in the exchanges. Telecommunication networks are evolving into intelligent networks that offer in addition to exchange-based services a number of services whose logic and data reside in a small number of centralized information sources that can be queried interrogated by the exchanges. The first steps toward intelligent networks IN were made by the Bell System in the early 1980s for 800-call services 1 . 800-numbers contain no routing information and have to be translated into routing numbers that have the North American numbering plan NANP format NPA-NXX-XXXX Section . The translation data are stored in network databases. This approach was taken because the translations require a large amount of data that has to be updated frequently. It is much simpler to add or change an entry in a few centralized databases than to enter these changes into every local exchange. 436 INTRODUCTION TO INTELLIGENT NETWORKS 437 The queries by the exchanges and the responses from the databases were transferred in CCIS direct signaling messages Section . After the divestiture of the Bell system the new regional telecoms started to deploy service control points SCP with databases for 800-calling and alternate billing services 2 . Messages between exchanges and SCPs are transferred by the SS7 signaling network