Installation manual

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part of Lucent was spun off. The move allowed Avaya to singularly
focus on the needs of enterprise customers. Avaya separated from
Lucent on Sept. 30, 2000 and began operating as an independent
company.
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More importantly, Avaya continues the Partner ACS system.
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The old “Bell System” (AT&T, Western Electric, etc.) provided multi-line
phone systems to users from the 1930s through the 1970s. These could be
classified into:
 Private Branch Exchanges (PBXs), starting with traditional operator cord-
boards and advancing quickly to automatic exchanges; these served 100 –
10,000 phones
 Key systems, managing a group of telephone lines across a group of users,
typically serving 5 – 100 users. Each user has access to a selection of
outside lines (or, installed “behind” a PBX, access to a selection of PBX
lines.
The most popular key system was the electromechanical 1A2 key system,
built around small circuit cards, one per telephone line. Phones could support
from 5 to 30 phone lines. Systems (Key Service Units) supported from 4 lines
to hundreds, the larger ones built of racks of 15-line units. In addition to
giving users access to designated lines, users could contact each other
through manual signaling (press a button, and a buzzer somewhere else
buzzed), or through intercoms (dial a number on an intercom line, and
another user’s phone buzzed.) A given intercom circuit generally supported
only 10 dial-able extensions, so was not terribly useful in larger offices, but
since in larger offices the key systems were often used behind PBXs, a user
could just dial the extension of the other user on a regular line.
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From Avaya’s corporate web site.