Centrex

Telephone services that your local telephone company provides from a Central Office (CO) located outside your business premises, including Centrex lines connected to the equipment controller and the featues available on those Centrex lines. (Your telephone company may call Centrex by another name.)

Centrex extension number

A short code (or “Centrex extension ID”) that can be used to dial another extension within the Centrex system. Typically, this is the last digits of the Centrex telephone number.

Centrex system

The total block of Centrex lines you subscribe to—all or some of which may be connected to the equipment controller for your system—together with the Centrex services associated with those lines. See also Premises equipment and System.

Centrex telephone number

The phone number that outside callers dial to reach an extension within the Centrex system.

Combination extension

An extension that has two devices connected to it using a special connector called a bridging adapter. Combination extensions can connect two industry-standard devices or an industry-standard device and an MLS- or MLC-model phone, but not two MLS- or MLC-model phones.

Controller

See Equipment controller.

D

Doorphone

An AT&T proprietary phone that can be wall mounted outside your office or in a lobby to allow visitors to alert up to five system extensions by pressing a button. The doorphone includes a speaker and microphone, to allow two-way conversation between the doorphone and the phone that answers.

E

Equipment controller

The AT&T product that you purchased as part of your system. This product consists of a group of modules that connect Centrex lines coming into your building to the extensions in your system. The equipment controller also provides equipment features.

Equipment feature

A feature provided by your equipment controller (as opposed to a service provided by Centrex).

Equipment feature button

A programmable telephone button on an MLS- or MLC-model telephone that enables you to access an equipment feature with one touch, simply by pressing the button. See also Auto Dial button and Programmable button.

Expansion carrier

The optional component of the AT&T equipment controller that can be connected to the primary carrier to expand your system’s line and extension capacity. See also Primary carrier.

Expansion processor module

The main module of the expansion carrier, which must be installed in the center slot of the expansion carrier. This AT&T module extends the primary carrier’s management capabilities to the 206 and 400 modules installed in the expansion carrier. See also Primary processor module.

Extension

A destination in the system that can be dialed.

Extension jack

The location on 206 modules that allows you to connect phones (or other telecommunications devices) to the equipment controller.

Extension jack number

The number assigned to each extension jack on a 206 module. Extension jack numbers run consecutively from 10 through 33 (for a two-carrier configuration).

Extension Programming

A method of telephone programming that lets users program their own extensions from their MLS- or MLC-model phones. Extension Programming is an alternative to Centralized Telephone Programming.

GL-2Glossary

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AT&T II manual GL-2Glossary, Centrex
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II specifications

AT&T II, a pivotal case in the landscape of telecommunications regulation, emerged from the expansive antitrust actions against the American Telephone and Telegraph Company (AT&T). Following World War II, AT&T had established itself as a telecommunications behemoth, monopolizing the market. The ramifications of this dominance spurred a significant shift in regulatory measures, leading to the dissolution of the Bell System in 1984, which consisted of AT&T and its regional operating companies.

One key feature of AT&T II is its emphasis on promoting competition in the telecommunications sector. The court's decision aimed to dismantle the monopolistic practices that had stifled innovation and restricted consumer choice. By encouraging competition among various service providers, the ruling paved the way for an environment where new technologies could flourish.

The technologies that emerged post-AT&T II significantly transformed the telecommunications landscape. The introduction of new digital switching systems allowed for improved call quality and increased network efficiency. The evolution of fiber-optic technology also played a crucial role, enabling faster transmission speeds and greater data capacity. Moreover, innovative services, such as mobile telephony and broadband internet, proliferated as competition increased.

Another characteristic of AT&T II is its focus on accessibility and consumer protection. The ruling mandated that telecommunications services be available to a broader swath of the population, ensuring that underserved communities had access to essential communication services. This shift not only democratized access but also laid the groundwork for the modern internet revolution, fostering the growth of the digital economy.

The impact of AT&T II can also be seen in the regulatory frameworks that followed. The Federal Communications Commission (FCC) adopted policies aimed at enhancing market transparency and ensuring fair practices among competitors. These regulatory changes helped to create a more equitable playing field, allowing smaller companies to compete against established giants.

In summary, AT&T II marked a turning point in telecommunications history, characterized by a focus on competition, technological advancements, and consumer protection. The dissolution of AT&T's monopoly allowed for the rapid evolution of technology and services, ultimately benefiting consumers and fostering an environment ripe for innovation. This ruling not only redefined the telecommunications industry but also set a precedent for how markets are regulated in the United States.
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