Economics of Telephone Relay Applications
01 January 1954
The telephone central office of today is in part an enormous computing machine which, upon instructions from the customer, given by his dial, calculates how to find the called party; then the remaining mechanism completes the call. This machine is composed largely of interconnected relays, used in enormous quantities. Every dial call in a large city involves around 1000 relays. A typical large office contains more than 60,000 of them; in fact, the3r are used so extensively that the Western Electric Company manufactures about ten of them for every new subscriber, and their output is figured in tens of millions per year. It is not 218 ECONOMICS OF T E L E P H O N E RELAY APPLICATIONS '219 surprising that relay use has an enormous influence on the cost of the central office -- not just because of relay purchase cost but also the relay's influence on other office factors. For example, the size of the power plant and the total number of equipments for common control, which depend on the functioning time of the relays, are decided by the relay characteristics. In the application of relays, then, it may well prove that the largest economies can be realized by spending a little more for each relay in the beginning in order to save still more in the cost of the power plant, common control equipment, size of the building, and so forth. It has been found that attention to ways of optimizing the application costs for relays can lead to an appreciably lower cost central office, and this paper will illustrate a few cases of how such a problem is approached.