About Our Technology

This page is under construction. When completed, it will provide full descriptions of:

  • How the telephone works
  • How relays work
  • How 1A Key Systems work
  • How 1A2 Key Systems work

For general interest, following is a description of a Typical Key System, and how it can be configured:

Prior to the convergence of communications and computing technologies, Key Telephone Systems for business were assembled by skilled craftsmen using electromechanical (analog) components.

Typically, a business telephone system comprises terminal equipment (telephone sets and add-ons), a network of cables, and a package of central equipment, the Key Service Unit, that powers and controls the phone system.

For most business users, the telephone sets themselves are the only visible component of the system. Business systems can be configured to meet almost any specification, but the majority of uses can be met with six-, ten- or twenty-button sets. One button per set is reserved for the 'Hold' function. All others are available for CO line access, intercom, or paging. The buttons can be made to function in a wide variety of other ways too.

A simple phone system for small business may include, for example, eight ten-button sets, each equipped with, say, six lines. (This would be described as an eight-by-six system). Any user would have access to any of the six lines; any line could be put on Hold and retrieved from any other telephone.

In this example, six lines plus Hold would occupy seven of the available ten buttons. Often, another button may serve as intercom/paging, permitting communications inside the office environment. The remaining two buttons could remain vacant to accommodate future expansion.

Add-ons to telephone sets are most common at the Receptionist position, or in Executive offices. The most useful tool for Reception is a Busy Lamp Field (BLF). Essentially a bank of lights, each of which corresponds to a set, the BLF reveals whether any phone is off-hook (light on) or on-hook (light off). By reading the lamps, the Receptionist can ascertain when an individual is on the phone, inform the caller, put the call on Hold, then instruct (by intercom) the called party when he/she is free to retrieve the call from Hold.

For Executives, typical add-ons include 'Handsfree' devices that allow conversations without the handset; and automatic dialers that eliminate the need to dial every digit of a telephone number.

The Key Service Unit is the central equipment that controls the telephone system. It is this Unit to which all wiring in the system eventually return. Cables are typically 25-or 50-pair (24 ga.), and are terminated on 66-type distribution blocks. Occasionally, where necessary, BIX-type blocks can also be used.

Depending on the size of the phone system, the KSU can range from the size of a breadbox to a seven-foot tall equipment rack. In all cases, the KSU must be custom built to perform the specified functions, and to allow for futurechanges or expansion. Whether small or large, a KSU will contain a power supply, ringing generator, and a variety of electromechanical relays that do the unseen work of the Business Telephone System.

Scroll to Top