Telecom Basics, Second Edition
This guide presents the groundwork of telecom technolgies, network, systems, and call processing.
TABLE OF CONTENTS Telecom Basics, Second Edition
Chapter 9: Systems
Systems are either common to all users or privately leased by a customer for some specific application. Telecommunications networks serve as interconnection points between end-users. Until the late 1990 s, technology, cost and regulatory limitations have restricted most systems to offering specific types of services such as voice, data, or video transmission. The traditional categories of systems include local exchange networks (LECs), private telephone systems, inter-exchange telephone networks (long distance), cable television systems, data networks, and wireless networks.
Public Switched Telephone Networks (PSTNs)
Local exchange carriers (LECs) or post and telegraph and telecommunications (PTT) companies provide telephone services directly to residential and business customers located within a localized geographic area. Typically, these telephone companies provide services via copper lines that extend from a local carrier s switching facilities to the end customer s premises equipment (CPE). This is referred to local loop.
Until the early 1990 s, most countries had a single company that provided local telephone services. This company was either owned or highly regulated by the government. To increase competition and reduce telephone service prices to consumers, some governments have begun to allow other companies to provide basic (local) telephone service. These competitive local exchange company (CLEC) or competitive access providers (CAPs) provide alternative connections to the public switched telephone networks (PSTN). The established telephone companies are now called the incumbent local exchange carriers (ILECs),
Traditional incumbent local exchange company (ILEC) may be connected with one or more competitive local exchange companies (CLECs) who provide local telephone service in a defined geographic...
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