Each telephone is connected (either directly or through a wall jack) to an extension jack on the equipment controller. Each extension jack on the controller is identified by an extension jack number. Extension jack numbers run from 10 through 33 (if you have the maximum number of extensions that can be used with your premises equipment).

Line jack numbers and extension jack numbers are required for many of the programming procedures that you use to customize your premises equipment.

Equipment Controller

555-1000

555-1001

555-1002

Default Primary

Line Assignments

Line Jack 01

Line Jack 02

Line Jack 03

Ext. Jack 10

Ext. Jack 11

Ext. Jack 12

Centrex Ext. 1000

Centrex Ext. 1001

Centrex Ext. 1002

Figure 3-1. Centrex and Equipment Line Numbers

Figure 3-1 shows line jack numbers and extension jack numbers in relation to telephone numbers and Centrex extension numbers in a very small (three-telephone) system. The three lines in this example (555-1000, 555-1001, and 555-1002) use the last four digits of the phone number as the Centrex extension number. The first line has Centrex extension number 1000; it is connected to the first line jack on the equipment controller (line jack 01), and serves as the primary line for the phone connected to extension jack 10. The other two lines are connected to line jacks 02 and 03, and provide primary lines for the phones connected to extension jacks 11 and 12, respectively.

NOTE:

Figure 3-1 shows only primary line assignments. By default, the equipment controller assigns all lines to the phone connected to extension jack 10, but only the first line is primary.

3-4Using the Equipment

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AT&T II manual Ext. Jack Centrex Ext, Centrex and Equipment Line Numbers

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.