An Experimental Remote Controlled Line Concentrator

261 261 262 263 264 266 267 268 269 270 270 272 273 274 279 280 282 284 286 287 288 290 291 The equipment which provides for the switching of telephone connections has always been located in what have been commonly called "central offices". These offices provide a means for the accumulation of all switching equipment required to handle the telephone needs of a community or a section of the community. The telephone building in which one or more central offices are located is sometimes referred to as the "wire center" because, like the spokes of a wheel, the wires which serve local telephones radiate in all directions to the telephones of the community. A new development, made possible largely by the application of devices and techniques new to the telephone switching field, has recently been tried out in the telephone plant and promises to change much of the present conception of "central" offices and "wire" centers. It is known as a "line concentrator" and provides a means for reducing the amount of outside plant cables, poles, etc., serving a telephone central office by dispersing the switching equipment in the outside plant. It is not a new concept to reduce outside plant by bringing the switching equipment closer to the telephone customer but the technical difficulties of maintaining complex switching equipment and the cost of controlling such equipment at a distance have in the past been formidable obstacles to the development of line concentrators. With the invention of low power, small-sized, long-life devices such as transistors, gas tubes, and sealed relays, and their application to line concentrators, and with the development of new local switching systems with greater flexibility, it has been possible to make the progress described herein.